Isolation, purification and characterization of chymosin from riverine buffalo (Bubalos bubalis)

Biochemical characterization, and anti-inflammatory and antitumor activities of glycoprotein from lamb abomasum

ETHNOPHARMACOLOGICAL RELEVANCE

Lamb abomasum is used as an edible medicinal source in traditional Chinese medicine for the treatment of gastrointestinal disorders. Lamb abomasum sourced biochemical drug Lamb's trip extract and Vitamin B12 capsule used for the clinical treatment of chronic gastritis, gastric ulcer, and reversal of intestinal metaplasia. Therefore, claimed to have prevention of gastric cancer activity.

AIM OF THE STUDY

In this study, we aim to assess whether the glycoprotein has biological activity in the cure of gastric disorder and conduct a structure-activity relationship.

MATERIALS AND METHODS

Glycoproteins' extraction conditions were optimized by the response surface method and purified with DEAE-cellulose and Sephadex G-50 chromatography. Two homogenous glycoproteins' physiochemical structures were studied with electrophoresis, HPLC analysis, peroxide oxidation, and β-elimination, FT-IR, CD, LC-MS/MS, and EDS analysis. The antiinflammation activity of the glycoprotein was determined against COX-2 and LOX-15 enzyme inhibitory ability in vitro, and antitumor activity against HT-29 and HGC-25, and cytotoxicity on L-02 cells was determined in vivo with the MTT method.

RESULTS

The abomasum was abundant in glycoprotein and the extraction yield of glycoprotein was up to 24.6 ± 2.1% under optimized conditions. Two homogeneous glycoproteins SAGP-I and SAGP-II determined to be ribose-conjugated and sulfated glycoproteins with a molecular weight of 15.6 kDa and 6.4 kDa. And according to the structural analysis, SAGP-I was a mucin-type ribose-conjugated glycoprotein with 14 O-glycosylation and one N- glycosylation site. SAGP-I and SAGP-II have remarkable anti-inflammatory activity against COX-2 enzyme with the IC₅₀ of 17.64 ± 1.25 μg/mL and 16.14 ± 1.11 μg/mL, respectively. Meanwhile, the two glycoproteins showed strong antitumor activity against HT-29 with the EC₅₀ of 19.19 ± 1.46 μg/mL and 184.9 ± 5.6 μg/mL, respectively.

CONCLUSION

The Highly purified glycoprotein SAGP-1 and SAGP-II showed anti-inflammatory activity against the COX-2 enzyme, and antitumor activity against HT-29 human colon cancer cells and noun-inhibitory activity against LOX-15 enzyme and HGC-25. Both glycoproteins are ribose conjugated and sulfated whose characters are related to their anti-inflammatory and anti-tumor activity. Such results suggest the possibility of anti-inflammatory and pre-cancer activity. And in some degree explains the pharmacy of abomasum's traditional use in gastric disorder and clinical use of lamb abomasum APIs drugs' in gastric disorders and gastric cancer development. This study provides a preliminary basis for the further study of the per-cancer mechanism of lamb abomasum glycoprotein. And, would be the material basis of the clinical use of Lamb's trip extract and Vitamin B12 capsule.

Effects of microbial coagulants from Rhyzomucor miehei on composition, sensory and textural characteristics of long-ripened hard cheeses

The increasing use of rennet substitutes entails evaluating their performances on different types of cheese. The production of hard cheese using either microbial coagulants from Rhyzomucor miehei (MC) or calf rennet (CR) from different manufacturers was investigated in parallel cheese makings at three industrial dairies. Cheeses were analysed after 9, 12, 16 and 18 months of ripening. Minor differences in cheese composition were found between treatments, principally related to fat content. Cheeses produced with one out of the three MC showed slower primary proteolysis on both αs1- and αs0-casein, compared to the corresponding CR cheeses, indicating a different activity of this coagulant. The same cheeses also had significantly different sensory profiles at 9 months of ripening. Treatments did not differ in free amino acid composition nor in rheological parameters, regardless of ripening period. The long ripening of hard cheeses thus smooths possible differences attributable to MC.

Effect of Oryctolagus cuniculus (rabbit) rennet on the texture, rheology, and sensory properties of white cheese

Calf rennet has long been used in cheese-making. Because of calf rennet shortage and high cost, novel proteases were needed to meet industry's increasing enzyme demand. Recombinant chymosins and camel chymosin were started to be used in the industry. There is no study in the literature subjecting use of rabbit rennet in cheese production. Chemical, rheological, and sensorial characteristics of white cheese made with rabbit rennet were investigated in this study. Quality characteristics of rabbit rennet cheese (RC) were compared to cheeses produced with commercial calf (CC) and camel chymosins (CLC). RC and CLC exhibited higher hardness and dynamic moduli values throughout the storage as compared to CC. Although moisture levels of cheese samples were similar at day 60, CC had much lower hardness and dynamic moduli values than CLC and RC. While the appearance and structure were better for CLC, the highest odor and taste scores were obtained by RC during 60 days of storage. The results of this investigation proposed that rabbit rennet could be a suitable milk coagulant for white cheese production. Our results showed that rabbit rennet has comparable cheese-making performance with camel chymosin and could be a good alternative for calf chymosin.

Codon Optimization of the "Bos Taurus Chymosin" Gene for the Production of Recombinant Chymosin in Pichia pastoris

Codon optimization of the Bos taurus Chymosin gene (CYM) for its expression in Pichia pastoris was performed in this study. A synthetic CYM gene was designed in silico by replacing codons rarely used by P. pastoris with equivalent nucleotide combinations that codify for the same amino acid but that are more frequently encountered in the genome of P. pastoris. A total of 332 nucleotides were modified to optimize 289 codons. The synthetic CYM gene was cloned into the expression vector pPICZαA and transformed into P. pastoris. The transformed strains were grown in artificial media supplemented with glycerol as a carbon source to increase biomass and then cultured in a similar medium replacing glycerol with methanol as a carbon source to initiate gene induction. Raw extracts of the growth media exhibited milk-clotting activity of 146.11 SU/mL. Produced recombinant chymosin showed coagulant activity from 25 to 50 °C, and within a pH range of 5-6.9, having optimum activity at 35-40 °C, and pH 5.0. These results show that codon optimization is a viable strategy to improve CYM gene expression levels in P. pastoris for the production of recombinant chymosin.

Isolation and Partial Characterisation of Milk-clotting Aspartic Protease from Streblus asper

A rennin-like milk-clotting protease from the twigs of Streblus asper was purified by a factor of 65 times with 36% recovery using ethanol precipitation, ion-exchange and size-exclusion chromatographic techniques. The enzyme was found to be monomeric in nature having a molecular mass of 55kDa. The enzyme acts optimally at 55°C and was stable in the temperature range of 30–40°C. Easy enzyme inactivation by moderate heating, makes this protease extract potentially useful for cheese production. The purified enzyme is an acid protease with an optimum pH of 5.5 and it retained 96% of its residual activity between pH 5.0 and 6.0. Pepstatin A inhibited the proteinase activity, whereas iodoacetamide, phenylmethyl sulphonyl fluoride, β-mercaptoethanol and ethylenediaminetetraacetic acid had no significant inhibitory effect suggesting the presence of aspartic acid residue at the active site. The milkclotting aspartic protease showed predominant α-helical conformation in phosphate buffer as evidenced from circular dichroic spectroscopy.

High Milk-Clotting Activity Expressed by the Newly Isolated Paenibacillus spp. Strain BD3526

Paenibacillus spp. BD3526, a bacterium exhibiting a protein hydrolysis circle surrounded with an obvious precipitation zone on skim milk agar, was isolated from raw yak (Bos grunniens) milk collected in Tibet, China. Phylogenetic analysis based on 16S rRNA and whole genome sequence comparison indicated the isolate belong to the genus Paenibacillus. The strain BD3526 demonstrated strong ability to produce protease with milk clotting activity (MCA) in wheat bran broth. The protease with MCA was predominantly accumulated during the late-exponential phase of growth. The proteolytic activity (PA) of the BD3526 protease was 1.33-fold higher than that of the commercial R. miehei coagulant. A maximum MCA (6470 ± 281 SU mL⁻¹) of the strain BD3526 was reached under optimal cultivation conditions. The protease with MCA was precipitated from the cultivated supernatant of wheat bran broth with ammonium sulfate and purified by anion-exchange chromatography. The molecular weight of the protease with MCA was determined as 35 kDa by sodium dodecyl sulfate-polyacrylamide gels electrophoresis (SDS-PAGE) and gelatin zymography. The cleavage site of the BD3526 protease with MCA in κ-casein was located at the Met₁₀₆–Ala₁₀₇ bond, as determined by mass spectrometry analysis.

Milk-clotting mechanism of Dregea sinensis Hemsl. protease

Dregea sinensis Hemsl. is used as a milk coagulant to produce goat milk cakes in Yunnan, China. However, the composition of milk-clotting compounds and the related mechanism have not been reported. Crude protease was extracted from the stem, purified, and then separated with a Millipore ultrafiltration centrifuge tube. Cysteine protease (procerain B) was identified as the main milk-clotting protein through electrospray ionization mass spectrometry, and its molecular weight was 23.8 kDa. The protease can partially degrade α-casein (CN) and completely degrade β- and κ-CN, and κ-CN degradation resulted in milk clotting. The molecular weight and AA sequence of the peptide fractions were determined through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and a peptide sequencer, respectively. The enzyme cleaved κ-CN at Ala90-Gln91 and produced deputy κ-CN and caseinomacropeptide with molecular weights of 12 and 6.9 kDa, respectively. This cleavage site differed from the majority of chymosins cleaved at Phe105-Met106.

Purification, characterization, and milk coagulating properties of ginger proteases

Ginger proteases are used as milk coagulants in making a Chinese traditional milk product (Jiangzhinai or Jiangzhuangnai), suggesting their potential as a source of rennet substitute that might be applicable in the modern dairy industry. In this study, ginger proteases were extracted from fresh ginger rhizome by using phosphate buffer and subsequently purified by ion exchange chromatography. Ginger proteases, all with a molecular weight around 31 kDa, were found to exist in 3 forms with isoelectric point values around 5.58, 5.40, and 5.22, respectively. These enzymes had very similar biochemical behavior, exhibiting optimal proteolytic activity from 40 to 60 °C and maximum milk clotting activity at 70 °C. They were capable of hydrolyzing isolated α(S1)-, β-, and κ-casein, of which α(S1)-casein was most susceptible to the enzyme; κ-casein was hydrolyzed with a higher specificity than α(S1)- and β-casein. In addition, the ginger proteases exhibited a similar affinity for κ-casein and higher specificity with increasing temperature. Gel electrophoresis and mass spectra indicated that Ala90-Glu91 and His102-Leu103 of κ-casein were the preferred target bonds of ginger proteases. The milk clotting activity, affinity, and specificity toward κ-casein showed that ginger protease is a promising rennet-like protease that could be used in manufacturing cheese and oriental-style dairy foods.

Cloning and expression of buffalo active chymosin in Pichia pastoris

To date, only recombinant chymosin has been obtained in its active form from supernatants of filamentous fungi, which are not as good candidates as yeasts for large-scale fermentations. Since Bos taurus chymosin was cloned and expressed, the world demand for this protease has increased to such an extent that the cheesemaking industry has been looking for novel sources of chymosin. In this sense because buffalo chymosin has properties that are more stable than those of B. taurus chymosin, it may occupy a space of its own in the chymosin market. The main objective of the present work was the production of active recombinant buffalo chymosin in the culture supernatant of Pichia pastoris . This yeast has demonstrated its usefulness as an excellent large-scale fermentation tool for the secretion of recombinant foreign proteins. RNA was extracted from the abomasum of a suckling calf water buffalo ( Bubalus arnee bubalis ). Preprochymosin, prochymosin, and chymosin DNA sequences were isolated and expressed into P. pastoris. Only the recombinant clones of P. pastoris containing the prochymosin sequence gene were able to secrete the active form of the chymosin to the culture supernatant. This paper describes for the first time the production of active recombinant chymosin in P. pastoris without the need of a previous in vitro activation. The new recombinant yeast strain could represent a novel and excellent source of rennet for the cheesemaking industry.

Study on milk-clotting mechanism of rennet-like enzyme from glutinous rice wine: proteolytic property and the cleavage site on kappa-casein

Chinese Royal cheese, an ancient and attractive dairy product now in China, is made from milk coagulated with glutinous rice wine. In this paper, it was mainly studied on the proteolytic property toward proteins of bovine milk including caseins (CN) and whey proteins and the cleavage bond on the kappa-CN of rennet-like enzyme purified from glutinous rice wine by ion-exchange chromatography. Compared with whey protein, the rennet-like protease has substrate specificity toward CN but with different hydrolysis degrees among kappa-, alpha-, and beta-CN, and the alpha-CN was almost completely degraded, whereas kappa- and beta-CN partly showed hydrolysis in 12 h. The analysis for enzyme digestion by electrospray tandem mass spectrometry, Q-TOF2, and matrix-assisted laser desorption-ionization time-of-flight mass spectrometry revealed that the cleavage of protease from glutinous rice wine on kappa-CN mainly happens at the Thr94-Met95 bond, which is different from the most chymosin-sensitive bond, Phe105-Met106.

Purification and characterization of milk clotting enzyme from goat (Capra hircus)

Chymosin, the major component of rennet (milk clotting enzyme), is an acid protease produced in the fourth stomach of milk-fed ruminants including goat and sheep in the form of an inactive precursor prochymosin. It is responsible for hydrolysis of kappa-casein chain in casein micelles of milk and therefore, used as milk coagulant in cheese preparation. The present investigation was undertaken to purify and characterize goat (Capra hircus) chymosin for its suitability as milk coagulant. The enzyme was extracted from abomasal tissue of kid and purified nearly 30-fold using anion exchanger and gel filtration chromatography. Goat chymosin resolved into three major active peaks, indicating possible heterogeneity when passed through DEAE-cellulose ion exchange column. The purified enzyme had a molecular mass of 36 kDa on SDS-PAGE, which was further confirmed by Western blot analysis. The purified enzyme preparation was stable up to 55 degrees C with maximum activity at 30 degrees C. The milk clotting activity was decreased steadily as pH is increased and indicated maximum activity at pH 5.5. Proteolytic activity of goat chymosin increased with incubation time at 37 degrees C. Goat chymosin was found to be more thermostable than cattle chymosin and equally stable to buffalo chymosin.

Molecular cloning and expression in yeast of caprine prochymosin

We cloned and characterized a preprochymosin cDNA from the abomasum of milk-fed kid goats. This cDNA contained an open reading frame that predicts a polypeptide of 381 amino acid residues, with a signal peptide and a proenzyme region of 16 and 42 amino acids, respectively. Comparison of the caprine preprochymosin sequence with the corresponding sequences of lamb and calf revealed 99 and 94% identity at the amino acid level. The cDNA fragment encoding the mature portion of caprine prochymosin was fused in frame both to the killer toxin signal sequence and to the alpha-factor signal sequence-FLAG in two different yeast expression vectors. The recombinant plasmids were transformed into Kluyveromyces lactis and Saccharomyces cerevisiae cells, respectively. Culture supernatants of both yeast transformants showed milk-clotting activity after activation at acid pH. The FLAG-prochymosin fusion was purified from S. cerevisiae culture supernatants by affinity chromatography. Proteolytic activity assayed toward casein fractions indicated that the recombinant caprine chymosin specifically hydrolysed kappa-casein.