1
|
Scepankova H, Galante D, Espinoza-Suaréz E, Pinto CA, Estevinho LM, Saraiva J. High Hydrostatic Pressure in the Modulation of Enzymatic and Organocatalysis and Life under Pressure: A Review. Molecules 2023; 28:molecules28104172. [PMID: 37241913 DOI: 10.3390/molecules28104172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/19/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
The interest in high hydrostatic pressure (HHP) is mostly focused on the inactivation of deleterious enzymes, considering the quality-related issues associated with enzymes in foods. However, more recently, HHP has been increasingly studied for several biotechnological applications, including the possibility of carrying out enzyme-catalyzed reactions under high pressure. This review aims to comprehensively present and discuss the effects of HHP on the kinetic catalytic action of enzymes and the equilibrium of the reaction when enzymatic reactions take place under pressure. Each enzyme can respond differently to high pressure, mainly depending on the pressure range and temperature applied. In some cases, the enzymatic reaction remains significantly active at high pressure and temperature, while at ambient pressure it is already inactivated or possesses minor activity. Furthermore, the effect of temperature and pressure on the enzymatic activity indicated a faster decrease in activity when elevated pressure is applied. For most cases, the product concentration at equilibrium under pressure increased; however, in some cases, hydrolysis was preferred over synthesis when pressure increased. The compiled evidence of the effect of high pressure on enzymatic activity indicates that pressure is an effective reaction parameter and that its application for enzyme catalysis is promising.
Collapse
Affiliation(s)
- Hana Scepankova
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
- CIMO, Mountain Research Center Polytechnic Institute of Bragança, Campus Santa Apolónia, 5301-855 Bragança, Portugal
| | - Diogo Galante
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | | | - Carlos A Pinto
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Letícia M Estevinho
- CIMO, Mountain Research Center Polytechnic Institute of Bragança, Campus Santa Apolónia, 5301-855 Bragança, Portugal
| | - Jorge Saraiva
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| |
Collapse
|
2
|
Chen G, Du H, Jiang B, Miao M, Feng B. Activity of Candida rugosa lipase for synthesis of hexyl octoate under high hydrostatic pressure and the mechanism of this reaction. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2017.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
3
|
Li Y, Miao M, Chen X, Jiang B, Liu M, Feng B. Improving the catalytic behavior of inulin fructotransferase under high hydrostatic pressure. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2015; 95:2588-2594. [PMID: 25565432 DOI: 10.1002/jsfa.7071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/08/2014] [Accepted: 12/26/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND The demand for difructose anhydride III (DFA III), a novel functional sweetener, is growing continuously. It is produced from inulin by inulin fructotransferase (IFTase). In this study, high hydrostatic pressure (HHP), as a clean technology, was first applied to further improve the catalytic efficiency of IFTase in the process. RESULTS The maximum activity of IFTase was obtained under 200 MPa at 60 °C. Meanwhile, HHP lowered the energy barrier necessary for the enzymatic reaction and decreased the volume between the reactants and the transition state. Under this condition, the optimal pH for the enzymatic reaction shifted from 5.5 to 6.0. The activity was further enhanced by 65.2% in the presence of 1.5 mol L(-1) NaCl. CONCLUSION The catalytic reaction of IFTase was performed under HHP for the first time. HHP, as a promising green technology for bioconversion, significantly accelerated the enzymatic reaction under the appropriate operational conditions.
Collapse
Affiliation(s)
- Yungao Li
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Ming Miao
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Xiangyin Chen
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Bo Jiang
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Miao Liu
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Biao Feng
- State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| |
Collapse
|
4
|
Wannicke N, Frindte K, Gust G, Liskow I, Wacker A, Meyer A, Grossart HP. Measuring bacterial activity and community composition at high hydrostatic pressure using a novel experimental approach: a pilot study. FEMS Microbiol Ecol 2015; 91:fiv036. [DOI: 10.1093/femsec/fiv036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2015] [Indexed: 11/12/2022] Open
|
5
|
Hydrogen-limited growth of hyperthermophilic methanogens at deep-sea hydrothermal vents. Proc Natl Acad Sci U S A 2012; 109:13674-9. [PMID: 22869718 DOI: 10.1073/pnas.1206632109] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microbial productivity at hydrothermal vents is among the highest found anywhere in the deep ocean, but constraints on microbial growth and metabolism at vents are lacking. We used a combination of cultivation, molecular, and geochemical tools to verify pure culture H(2) threshold measurements for hyperthermophilic methanogenesis in low-temperature hydrothermal fluids from Axial Volcano and Endeavour Segment in the northeastern Pacific Ocean. Two Methanocaldococcus strains from Axial and Methanocaldococcus jannaschii showed similar Monod growth kinetics when grown in a bioreactor at varying H(2) concentrations. Their H(2) half-saturation value was 66 μM, and growth ceased below 17-23 μM H(2), 10-fold lower than previously predicted. By comparison, measured H(2) and CH(4) concentrations in fluids suggest that there was generally sufficient H(2) for Methanocaldococcus growth at Axial but not at Endeavour. Fluids from one vent at Axial (Marker 113) had anomalously high CH(4) concentrations and contained various thermal classes of methanogens based on cultivation and mcrA/mrtA analyses. At Endeavour, methanogens were largely undetectable in fluid samples based on cultivation and molecular screens, although abundances of hyperthermophilic heterotrophs were relatively high. Where present, Methanocaldococcus genes were the predominant mcrA/mrtA sequences recovered and comprised ∼0.2-6% of the total archaeal community. Field and coculture data suggest that H(2) limitation may be partly ameliorated by H(2) syntrophy with hyperthermophilic heterotrophs. These data support our estimated H(2) threshold for hyperthermophilic methanogenesis at vents and highlight the need for coupled laboratory and field measurements to constrain microbial distribution and biogeochemical impacts in the deep sea.
Collapse
|
6
|
Deusner C, Meyer V, Ferdelman TG. High-pressure systems for gas-phase free continuous incubation of enriched marine microbial communities performing anaerobic oxidation of methane. Biotechnol Bioeng 2010; 105:524-33. [DOI: 10.1002/bit.22553] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
7
|
|
8
|
Imai T, Yasujima D, Siddiqui MA. An instant measurement of oxidoreductase activity above 100°C by monitoring the absorbance change. J Biosci Bioeng 2004; 97:336-8. [PMID: 16233639 DOI: 10.1016/s1389-1723(04)70215-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Accepted: 11/11/2003] [Indexed: 11/20/2022]
Abstract
A conventional absorbance monitoring method using a cuvette covered with a tight rubber cap was found to be applicable for measuring oxidoreductase activity at temperatures up to 115 degrees C. Using this method, the optimal temperatures of the enzymes, including oxygen-sensitive enzymes from a hyperthermophilic archaeon Thermococcus profundus, were determined.
Collapse
Affiliation(s)
- Takeo Imai
- Department of Life Science, Graduate School of Life Science, Rikkyo (St. Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
| | | | | |
Collapse
|
9
|
Frankenberg RJ, Andersson M, Clark DS. Effect of temperature and pressure on the proteolytic specificity of the recombinant 20S proteasome from Methanococcus jannaschii. Extremophiles 2003; 7:353-60. [PMID: 12820035 DOI: 10.1007/s00792-003-0330-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 03/17/2003] [Indexed: 10/26/2022]
Abstract
The hydrolytic specificity of the recombinant 20S proteasome from the deep-sea thermophile Methanococcus jannaschii was evaluated toward oxidized insulin B-chain across a range of temperatures (35 degrees, 55 degrees, 75 degrees, and 90 degrees C) and hydrostatic pressures (1, 250, 500, and 1,000 atm). Of the four temperatures considered, the same maximum overall hydrolysis rate was observed at both 55 degrees and 75 degrees C, which are much lower than the T(opt) of 116 degrees C previously observed for a small amide substrate (Michels and Clark 1997). At 35 degrees C the rates of cleavage were highest at the carboxyl side of glutamine and leucine, whereas at the three higher temperatures, the most rapid cleavages occurred after leucine and glutamic acid residues. The distribution of proteolytic fragments and the cleavage sequence also varied between the lowest and higher temperatures. Application of hydrostatic pressure did not increase proteasome activity, as observed previously for the amide substrate (Michels and Clark 1997), but instead significantly reduced the overall conversion of the polypeptide substrate. Overall cleavage patterns observed for the recombinant M. jannaschii proteasome were similar to those reported previously for Thermoplasma acidophilum (Akopian et al. 1997) and human proteasomes (Dick et al. 1991), indicating that proteasome specificity has been conserved despite significant environmental diversity.
Collapse
|
10
|
Affiliation(s)
- M M Sun
- Department of Chemical Engineering, University of California, Berkeley, California 94720, USA
| | | |
Collapse
|
11
|
Vieille C, Zeikus GJ. Hyperthermophilic enzymes: sources, uses, and molecular mechanisms for thermostability. Microbiol Mol Biol Rev 2001; 65:1-43. [PMID: 11238984 PMCID: PMC99017 DOI: 10.1128/mmbr.65.1.1-43.2001] [Citation(s) in RCA: 1384] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enzymes synthesized by hyperthermophiles (bacteria and archaea with optimal growth temperatures of > 80 degrees C), also called hyperthermophilic enzymes, are typically thermostable (i.e., resistant to irreversible inactivation at high temperatures) and are optimally active at high temperatures. These enzymes share the same catalytic mechanisms with their mesophilic counterparts. When cloned and expressed in mesophilic hosts, hyperthermophilic enzymes usually retain their thermal properties, indicating that these properties are genetically encoded. Sequence alignments, amino acid content comparisons, crystal structure comparisons, and mutagenesis experiments indicate that hyperthermophilic enzymes are, indeed, very similar to their mesophilic homologues. No single mechanism is responsible for the remarkable stability of hyperthermophilic enzymes. Increased thermostability must be found, instead, in a small number of highly specific alterations that often do not obey any obvious traffic rules. After briefly discussing the diversity of hyperthermophilic organisms, this review concentrates on the remarkable thermostability of their enzymes. The biochemical and molecular properties of hyperthermophilic enzymes are described. Mechanisms responsible for protein inactivation are reviewed. The molecular mechanisms involved in protein thermostabilization are discussed, including ion pairs, hydrogen bonds, hydrophobic interactions, disulfide bridges, packing, decrease of the entropy of unfolding, and intersubunit interactions. Finally, current uses and potential applications of thermophilic and hyperthermophilic enzymes as research reagents and as catalysts for industrial processes are described.
Collapse
Affiliation(s)
- C Vieille
- Biochemistry Department, Michigan State University, East Lansing, Michigan 48824, USA
| | | |
Collapse
|
12
|
Canganella F, Gambacorta A, Kato C, Horikoshi K. Effects of hydrostatic pressure and temperature on physiological traits of Thermococcus guaymasensis and Thermococcus aggregans growing on starch. Microbiol Res 2000; 154:297-306. [PMID: 10772151 DOI: 10.1016/s0944-5013(00)80003-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effects of temperature and hydrostatic pressure on growth of two novel Thermococcus species, T. guaymasensis and T. aggregans, were investigated. These archaea, isolated from the Guaymas Basin hydrothermal vent site at 2000 meters depth, are able to grow on starch in sulfur-depleted medium producing significant amounts of amylases and pullulanases. At 85 degrees C, T. guaymasensis exhibited a barophilic response at 20 and 35 MPa but inhibition of growth occurred at 50 MPa; at 50 MPa, cell replication was repressed, the mean cell size increased, and production of starch-hydrolysing enzymes was significantly stimulated. Barophily was also expressed by T. guaymasensis under 20 MPa at sub-optimal temperature (70 C) but morphological alterations of cells were observed earlier (35 MPa). No barophily was exhibited by T. aggregans at 85 degrees C. In this case, cell replication was repressed at 20 MPa and remarkable inhibition of growth occurred at 50 MPa. Only when T. aggregans was cultivated at 75 degrees C, a significant barophilic response was exhibited at 20 MPa, as shown by the rate of replication and metabolism. These results show that Thermococcus species, although isolated from the same ecosystem, differ with regard to the effects of pressure and temperature on cell physiology. The metabolic responses and their significance for potential biotechnological applications are also discussed.
Collapse
Affiliation(s)
- F Canganella
- Department of Agrobiology and Agrochemistry University of Tuscia, Viterbo, Italy.
| | | | | | | |
Collapse
|
13
|
Abstract
Enzymes synthesized by thermophiles (organisms with optimal growth temperatures > 60 degrees C) and hyperthermophiles (optimal growth temperatures > 80 degrees C) are typically thermostable (resistant to irreversible inactivation at high temperatures) and thermophilic (optimally active at high temperatures, i.e., > 60 degrees C). These enzymes, called thermozymes, share catalytic mechanisms with their mesophilic counterparts. When cloned and expressed in mesophilic hosts, thermozymes usually retain their thermal properties, suggesting that these properties are genetically encoded. Sequence alignments, amino acid content comparisons, and crystal structure comparisons indicate that thermozymes are, indeed, very similar to mesophilic enzymes. No obvious sequence or structural features account for enzyme thermostability and thermophilicity. Thermostability and thermophilicity molecular mechanisms are varied, differing from enzyme to enzyme. Thermostability and thermophilicity are usually caused by the accumulation of numerous subtle sequence differences. This review concentrates on the mechanisms involved in enzyme thermostability and thermophilicity. Their relationships with protein rigidity and flexibility and with protein folding and unfolding are discussed. Intrinsic stabilizing forces (e.g., salt bridges, hydrogen bonds, hydrophobic interactions) and extrinsic stabilizing factors are examined. Finally, thermozymes' potential as catalysts for industrial processes and specialty uses are discussed, and lines of development (through new applications, and protein engineering) are also proposed.
Collapse
Affiliation(s)
- C Vieille
- Department of Biochemistry, Michigan State University, East Lansing 48909, USA
| | | | | |
Collapse
|
14
|
Michels PC, Hei D, Clark DS. Pressure effects on enzyme activity and stability at high temperatures. ADVANCES IN PROTEIN CHEMISTRY 1996; 48:341-76. [PMID: 8791629 DOI: 10.1016/s0065-3233(08)60366-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- P C Michels
- Department of Chemical Engineering, University of California, Berkeley 94720, USA
| | | | | |
Collapse
|
15
|
Kaneshiro SM, Clark DS. Pressure effects on the composition and thermal behavior of lipids from the deep-sea thermophile Methanococcus jannaschii. J Bacteriol 1995; 177:3668-72. [PMID: 7601829 PMCID: PMC177081 DOI: 10.1128/jb.177.13.3668-3672.1995] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The deep-sea archaeon Methanococcus jannaschii was grown at 86 degrees C and under 8, 250, and 500 atm (1 atm = 101.29 kPa) of hyperbaric pressure in a high-pressure, high-temperature bioreactor. The core lipid composition of cultures grown at 250 or 500 atm, as analyzed by supercritical fluid chromatography, exhibited an increased proportion of macrocyclic archaeol and corresponding reductions in aracheol and caldarchaeol compared with the 8-atm cultures. Thermal analysis of a model core-lipid system (23% archaeol, 37% macrocyclic archaeol, and 40% caldarchaeol) using differential scanning calorimetry revealed no well-defined phase transition in the temperature range of 20 to 120 degrees C. Complementary studies of spin-labeled samples under 10 and 500 atm in a special high-pressure, high-temperature electron paramagnetic resonance spectroscopy cell supported the differential scanning calorimetry phase transition data and established that pressure has a lipid-ordering effect over the full range of M. jannaschii's growth temperatures. Specifically, pressure shifted the temperature dependence of lipid fluidity by ca. 10 degrees C/500 atm.
Collapse
Affiliation(s)
- S M Kaneshiro
- Department of Chemical Engineering, University of California, Berkeley 94720, USA
| | | |
Collapse
|
16
|
Tsao JH, Kaneshiro SM, Yu SS, Clark DS. Continuous culture ofMethanococcus jannaschii, an extremely thermophilic methanogen. Biotechnol Bioeng 1994; 43:258-61. [DOI: 10.1002/bit.260430309] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
17
|
Pepper CB, Monbouquette HG. Issues in the culture of the extremely thermophilic methanogen,methanothermus fervidus. Biotechnol Bioeng 1993; 41:970-8. [DOI: 10.1002/bit.260411008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
18
|
Nelson CM, Schuppenhauer MR, Clark DS. High-pressure, high-temperature bioreactor for comparing effects of hyperbaric and hydrostatic pressure on bacterial growth. Appl Environ Microbiol 1992; 58:1789-93. [PMID: 1622255 PMCID: PMC195676 DOI: 10.1128/aem.58.5.1789-1793.1992] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We describe a high-pressure reactor system suitable for simultaneous hyperbaric and hydrostatic pressurization of bacterial cultures at elevated temperatures. For the deep-sea thermophile ES4, the growth rate at 500 atm (1 atm = 101.29 kPa) and 95 degrees C under hydrostatic pressure was ca. three times the growth rate under hyperbaric pressure and ca. 40% higher than the growth rate at 35 atm.
Collapse
Affiliation(s)
- C M Nelson
- Department of Chemical Engineering, University of California, Berkeley 94720-9989
| | | | | |
Collapse
|
19
|
Ludlow JM, Clark DS. Engineering considerations for the application of extremophiles in biotechnology. Crit Rev Biotechnol 1991; 10:321-45. [PMID: 2070423 DOI: 10.3109/07388559109038214] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Biotechnology may soon take greater advantage of extremophiles--microorganisms that grow in high salt or heavy metal concentrations, or at extremes of temperature, pressure, or pH. These organisms and their cellular components are attractive because they permit process operation over a wider range of conditions than their traditional counterparts. However, extremophiles also present a number of challenges for the development of bioprocesses, such as slow growth, low cell yield, and high shear sensitivity. Difficulties inherent in designing equipment suitable for extreme conditions are also encountered. This review describes both the advantages and disadvantages of extremophiles, as well as the specialized equipment required for their study and application in biotechnology.
Collapse
Affiliation(s)
- J M Ludlow
- Department of Chemical Engineering, University of California, Berkeley 94720
| | | |
Collapse
|
20
|
Shah NN, Clark DS. Partial Purification and Characterization of Two Hydrogenases from the Extreme Thermophile
Methanococcus jannaschii. Appl Environ Microbiol 1990; 56:858-63. [PMID: 16348172 PMCID: PMC184312 DOI: 10.1128/aem.56.4.858-863.1990] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
F
420
-nonreactive and F
420
-reactive hydrogenases have been partially purified from
Methanococcus jannaschii
, an extremely thermophilic methanogen isolated from a submarine hydrothermal vent. The molecular weights of both hydrogenases were determined by native gradient electrophoresis in 5 to 27% polyacrylamide gels. The F
420
-nonreactive hydrogenase produced one major band (475 kilodaltons), whereas the F
420
-reactive hydrogenase produced two major bands (990 and 115 kilodaltons). The F
420
-nonreactive hydrogenase consisted of two subunits (43 and 31 kilodaltons), and the F
420
-reactive hydrogenase contained three subunits (48, 32, and 25 kilodaltons). Each hydrogenase was active at very high temperatures. Methyl viologen-reducing activity of the F
420
-nonreactive hydrogenase was maximal at 80°C but was still detectable at 103°C. The maximum activities of F
420
-reactive hydrogenase for F
420
and methyl viologen were measured at 80 and 90°C, respectively. Low but measureable activity toward methyl viologen was repeatedly observed at 103°C. Moreover, the half-life of the F
420
-nonreactive hydrogenase at 70°C was over 9 h, and that of the F
420
-reactive enzyme was over 3 h.
Collapse
Affiliation(s)
- N N Shah
- Department of Chemical Engineering, University of California, Berkeley, California 94720
| | | |
Collapse
|