Study of proteolysis in river buffalo mozzarella cheese using a proteomics approach

The guarantee of the origin and quality of raw material is essential for the protection and valorization of Campana buffalo mozzarella cheese. The risk of utilization of semifinished products and stored milk in substitution for fresh milk is increasing, due to the continuous desire to reduce production costs. A proteomics approach and electrophoresis survey of retail mozzarella cheeses indicated different rates of proteolysis in the production of dairy industries. The use of fresh milk and correct cheesemaking protocol yielded only γ-caseins, which are derived from β-casein by plasmin, and para-κ-casein, which is derived from κ-casein by chymosin. The detection of abnormal hydrolysis resulting in β- and αS1-casein fragments, identified by mass spectrometry, indicates the use of stored milk or stored and pressed curd, or the reuse of unsold mozzarella cheese, to produce mozzarella. The formation of γ-caseins and other fragments during a long storage of raw materials at room or refrigeration temperature was ascribed to plasmin (endogenous milk enzyme), whereas formation of αS1-casein fragments, mainly αS1-I(6P)- and αS1-I(7P)-casein during the storage of curd was ascribed to the action of chymosin (exogenous enzyme) from rennet. Sodium dodecyl sulfate-PAGE and alkaline urea-PAGE permitted us to evaluate the freshness of the raw materials used in the manufacturing of buffalo mozzarella cheese and to reveal possible inappropriate preservation.

Primary structure of alpha-globin chains from river buffalo (Bubalus bubalis L.) hemoglobins

Primary structure analysis of the four river buffalo alpha-globin chains showed that haplotypes A and B differ from each other by a substitution at codon 64 that may encode Ala or Asn. The A haplotype encodes two alpha-globin chains, Ialpha1 and IIalpha3, which differ at positions 129 and 131: Ialpha1 has 64 Ala, 129 Phe, 131 Asn; IIalpha3 has 64 Ala, 129 Leu, 131 Ser. The B haplotype encodes two alpha-globin chains, Ialpha2 and IIalpha4, which differ at positions 10 and 11: Ialpha2 has 10 I1e, 11 Gln, 64 Asn; IIalpha4 has 10 Val, 11 Lys, 64 Asn. Apart from the Ala/Asn polymorphism at position 64, amino acid substitutions in allelic and nonallelic alpha-globin chains seem to have arisen by single point mutations. Detection of electrophoretically silent mutations due to neutral amino acid substitutions and their influence on the isoelectric point are discussed. Furthermore, primary structures of river buffalo alpha-globin chains are compared to other species of the Bovidae family to suggest evolutionary events that have characterized the amino acid substitutions of river buffalo hemoglobin.

Milk identification of different species: 13C-NMR spectroscopy of triacylglycerols from cows and buffaloes' milks

Triacylglycerols from cows and buffaloes' milk fat were investigated by 13C nuclear magnetic resonance (NMR) spectroscopy. By the addition of pure triacylglycerols standards, we identified the resonances of both milk fats, and the peaks were used for qualitative and quantitative analysis of acyl groups. Multivariate analysis treatment of triacylglycerols distribution and composition parameters enabled us to identify milk. This study shows that NMR can safely be used to quantitate milk fatty acid content, providing unique information for milk identification of different animal species.

Identical marker alleles in Podolic cattle (Bos taurus) and Indian zebu (Bos indicus)

In the context of biochemical marker research and in order to add new information on native breeds, the present work focuses on a local Southern Italy cattle, namely Italian Podolic. We provide the complete structural characterisation of alpha-lactalbumins and beta-globin chains isolated from Podolic cattle (Bos taurus). Given the unavailability of the complete sequence for alpha-lactalbumin A of taurine cattle in the literature, we intended to check its structure in order to ascertain the absence of any possible silent mutation. Screening the Podolic cattle, we found a new beta-globin variant not detectable by conventional methods. The presence of such a new variant might be helpful in the study of the Podolic population genetic structure and for a better knowledge of the gene pool per se, and in comparison with the other breeds. Structural analyses showed that the new beta-globin Podolic variant exhibited the same sequence as beta-globin Azebu. The alpha-lactalbumin A was the same as that isolated from zebu cattle (Bos indicus). The results are discussed in relation to the possible involvement of the two markers in the debate on the origin of the Podolic breed.

Interaction of putrescine with nuclear oligopeptides in the enterocyte-like Caco-2 cells

Intestinal cells are able both to synthesize and take up putrescine, the main compound of the metabolic polyamine pathway. Polyamine binding to nuclear macromolecules is thougth to modulate DNA synthesis and transcription. Our aim was to study the fate of putrescine when taken up from the medium in the enterocyte-like Caco-2 cells and to analyze its binding to nuclear proteins. After having incubated the cells with 14C-putrescine (0.8 microM), during cell replication and differentiation, the nuclei were separated by sequential centrifugations in a sucrose gradient. About 20% of the putrescine taken up by Caco-2 cells resulted in the nuclei in both proliferating and differentiated cells. The binding of polyamines to nuclear proteins was studied on nuclear extracts, separated by both alkaline polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) and gel permeation chromatography (GPC). No radioactivity was found in nuclear protein extracts when using the SDS-PAGE method. Conversely, in replicating cells, GPC showed that the greatest amount of radioactivity was present in the nuclear peaks corresponding to oligopeptides with a molecular weight of 4,800-8,000 daltons. High-performance liquid chromatography analysis showed the presence of putrescine and spermidine in the 8, 000-dalton protein peak, whereas in the 4,800-dalton peak spermine was found in addition to putrescine. The radioactive count in the HPLC separated polyamines showed that a small percentage of the radioactivity present in the 8,000 and 4,800-dalton GPC peaks was linked to spermine and spermidine, suggesting an interconversion of the supplemented putrescine. Conversely, in differentiated cells, the nuclear oligopeptides did not reveal any radioactivity or any polyamines, suggesting that the binding of polyamines to nuclear oligopeptides is exclusively concerned with replicating cells.

Identification of C-terminally truncated forms of beta-lactoglobulin in whey from Romagnola cows' milk by two dimensional electrophoresis coupled to mass spectrometry

Four minor protein components were detected in whey from Romagnola cows' milk by polyacrylamide gel isoelectric focusing and two dimensional gel electrophoresis. Individual protein spots were transferred by electroblotting on to a polyvinylidene difluoride membrane and isolated by cutting out the relevant area. After in situ trypsinolysis, a portion of the digest was analysed directly by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The mass profile allowed us to establish a correlation between beta-lactoglobulins A and B and the four minor whey protein components. They were identified as C-terminally truncated beta-lactoglobulin A and B variants with missing N-terminal peptides, beyond residues in the range 100-123 and 136-147 respectively. Two of the minor components were related to beta-lactoglobulin A and two to beta-lactoglobulin B.

Bovine hemoglobin alpha-globin chain polymorphism: primary structure determination of two new genetic variants by mass spectrometry and amino acid sequencing

The present work describes the biochemical procedures used to identify the cause of a quantitative and qualitative hemoglobin polymorphism found in Podolian cattle. First, to analyze the different phenotypes, isoelectric focusing (IEF) of hemoglobins and RP-HPLC of globin chains was carried out; secondly, to determine accurately the globin molecular masses, electrospray mass spectrometry was performed and finally to check the entire amino acid sequences of the proteins, several enzymatic digests were analyzed by fast atom bombardment mass spectrometry (FAB-MS) and Edman degradation procedure. As to the qualitative polymorphism, the results of RP-HPLC show the presence of two alpha-globin variants to which the extensive mass spectrometric analysis attributed a molecular mass of 15,026.47 +/- 0.44 Da and 15,079.86 +/- 0.66 Da and whose respective primary structure differed from that of the common alpha-globin chain in the amino acid substitution Asn-->Ser at position 131 and the other in the replacement of the histidine residue at position 89 with tyrosine. As to the quantitative polymorphism, on the basis of the expression gradient found out in the duplicated alpha genes of several mammals, we conceive that the alpha 89 His-->Tyr is an allelic form of the I alpha gene while the alpha 131Asn-->Ser is an allelic form of the II alpha gene.

Two novel classes of neuroactive fatty acid amides are substrates for mouse neuroblastoma 'anandamide amidohydrolase'

The endogenous cannabimimetic substance, anandamide (N-arachidonoyl-ethanolamine) and the recently isolated sleep-inducing factor, oleoyl-amide (cis-9,10-octadecenoamide), belong to two neuroactive fatty acid amide classes whose action in mammals has been shown to be controlled by enzymatic amide bond hydrolysis. Here we report the partial characterisation and purification of 'anandamide amidohydrolase' from membrane fractions of N18 neuroblastoma cells, and provide evidence for a further and previously unsuspected role of this enzyme. An enzymatic activity catalysing the hydrolysis of [14C]anandamide was found in both microsomal and 10,000 x g pellet fractions. The latter fractions, which displayed the highest Vmax for anandamide, were used for further characterisation of the enzyme, and were found to catalyse the hydrolysis also of [14C]oleoyl-amide, with an apparent Km of 9.0 +/- 2.2 microM. [14C]anandamide- and [14C]oleoyl-amide-hydrolysing activities: (i) exhibited identical pH- and temperature-dependency profiles; (ii) were inhibited by alkylating agents; (iii) were competitively inhibited by the phospholipase A2 inhibitor arachidonyl-trifluoromethyl-ketone with the same IC50 (3 microM); (iv) were competitively inhibited by both anandamide (or other polyunsaturated fatty acid-ethanolamides) and oleoyl-amide. Proteins solubilised from 10,000 x g pellets were directly analysed by isoelectric focusing, yielding purified fractions capable of catalysing the hydrolysis of both [14C]anandamide and [14C]oleoyl-amide. These data suggest that 'anandamide amidohydrolase' enzymes, such as that characterised in this study, may be used by neuronal cells also to hydrolyse the novel sleep-inducing factor oleoyl-amide.

Electrospray mass spectrometric analysis of river buffalo (Bubalus bubalis) hemoglobins. Re-examination of alpha 1 and alpha 3 globin chain sequences

1. The accurate molecular weight of the globin chains from river buffalo hemoglobin components has been determined by means of electrospray mass spectrometry. 2. The ES/MS analysis demonstrated that all the buffalo Hb components share a common beta chain whose mass value coincides with that expected on the basis of the reported sequence. 3. The AA phenotype alpha 1 and alpha 3 globin chains exhibited a 30 Da mass difference as compared to their predicted molecular weights. Careful re-examination of the two alpha globin sequences by FAB/MS revealed the occurrence of sequence errors and hence the correct primary structure of both alpha chains was established.

Haemoglobin I: a new beta-globin chain variant found in sheep of Italian breeds

A rather common haemoglobin variant was detected in the Sardinian and Altamurana sheep breeds. The mutated globin chain appears to be produced under the control of an allele at the HBB locus and due to a neutral amino acid substitution. The variant will be provisionally referred to as the Hb I.

Evolution of ruminant hemoglobins. Thermodynamic divergence of ox and buffalo hemoglobins

The ligand-binding properties of hemoglobins from two homozygote phenotypes (AA and BB) of water buffalo (Bubalus bubalis) have been characterized by equilibrium and kinetic techniques. In the case of the BB phenotype, the two constituent hemoglobins have been purified and separately analysed. Buffalo hemoglobins display the reduced sensitivity to organic phosphates characteristic of ruminant hemoglobins, their physiological effector probably being the chloride ion. In contrast to the other known hemoglobins from ruminants, all the hemoglobins from the water buffalo display a significant temperature sensitivity, the delta H for oxygen binding in the presence of physiological effectors approaching that of human hemoglobin (delta H = -30.5 kJ/mol O2). This discrepancy with the other ruminant hemoglobins (e.g. ox, delta H = -10.4 kJ/mol O2), whose primary structure is very similar to that of buffalo, hemoglobins might be correlated to the different habitat and phylogenetic history of the two subfamilies (Bos and Bubalus) of Bovidae.

River buffalo (Bubalus bubalis L.) AA phenotype haemoglobins: characterization by immobiline polyacrylamide gel electrophoresis and high performance liquid chromatography and determination of the primary structure of the constitutive chains by mass spectrometry

1. Polyacrylamide gel electrophoresis in ultra-narrow immobilized pH gradient shifted the "Hb fast" band of AA buffalo phenotype haemoglobin into two components which were named Hb1 and Hb3. 2. Urea/Triton electrophoresis and reversed-phase HPLC demonstrated that Hb1 and Hb3 differ in the presence of two structurally distinct alpha chains (alpha 1 and alpha 3), also suggesting that the alpha chains must differ for neutral amino acid substitution. 3. Extensive mass spectrometric analysis on several digests (FAB overlapping) meant to determine the complete sequence of the constituent chains. 4. Two amino acid replacements (Lys 18----His and Asn 116----His) were present in the beta chain with respect to the bovine (A phenotype) chain, whereas the alpha 1 and alpha 3 globins were found to contain four amino acid replacements compared to the bovine alpha, three of which were identical (Glu 23----Asp, Glu 71----Gly and Phe 117----Cys) and, notably, an insertion of Ala at position 123-124. 5. Furthermore, alpha 1 contains Phe at position 130 whereas alpha 3 contains Ser at position 132 (following the modified numbering as a consequence of the Ala insertion).

Electrophoretic and chromatographic evidence for allelic polymorphisms in the river buffalo alpha-globin gene complex

Isoelectric focusing in the ultranarrow immobilized (7.1-7.5) pH gradient (IPG) of hemoglobin and high-performances liquid chromatography (HPLC) of globin chains were used to investigate Hb polymorphism in Italian river buffalo. Six different phenotypes, each characterized by two or four different Hbs, were detected by IPG, whereas two different II alpha-globin chains were separated from two different I alpha-chains by HPLC. Two alpha-chains (I alpha 1 and II alpha 3), and Hbs with similar mobilities (Hb1 and Hb3), were associated with the AA Hb phenotype: two alpha-chains (I alpha 2 and II alpha 4), and Hbs with different mobilities (Hb2 and Hb4), were associated with the BB phenotype: two sets of doublet Hbs were associated with the AB phenotype, thus suggesting allelic polymorphisms at the two alpha loci. An allele at the beta locus is responsible for increasing to as many as eight the number of different Hbs, thus further complicating the notable Hb polymorphism of the river buffalo.

Evidence for the presence of two different beta-globin chains in the hemoglobin of the river buffalo (Bubalus bubalis L.)

1. Hemoglobin (Hb) of the river buffalo (Bubalus bubalis L.) was studied by employing isoelectric focusing (IEF) in the 6.7-7.7 pH range and by IEF in ultra-narrow immobilized pH gradient (IPG) 7.1-7.5. 2. Three Hb BB phenotypes were identified which were characterized by sets of two or four Hbs with different isoelectric points. 3. These type were called BB, BsBs and BBs, the Bs phenotype showing Hbs with slightly slower mobility. 4. Analysis of constituent globin chains by acid urea polyacrylamide gel electrophoresis in the presence of Triton X-100, provided clear evidence of a novel polymorphism at the beta-globin level. 5. Titration curves of beta-globins from heterozygous Hb BBs indicated a single curve thus suggesting the absence of a net charge in all the pH field. 6. A neutral-to-neutral amino acid replacement probably differentiates the two beta-globins.

Fast isoelectric focusing of milk proteins on small ultrathin polyacrylamide gels containing urea

The preparation of 0.45 mm thin polyacrylamide gels, containing urea, for horizontal micro isoelectric focusing of milk proteins with PhastSystem is described. Isoelectric focusing in the small gels, stained either with Coomassie Brilliant Blue R-250 or with the more sensitive silver stain, affords a fast and sensitive procedure for an analysis of milk and cheese proteins. The procedure can be effectively exploited in detecting adulteration in ovine cheese with bovine milk.

Water buffalo (Bubalus bubalis) hemoglobins: an electrophoretic and chromatographic study

1. Hemoglobins from three phenotypes of Italian water buffalo (Bubalus bubalis), named AA, AB and BB, were selected by starch gel electrophoresis at alkaline pH and analyzed using polyacrylamide gel isoelectric focusing and subsequent analysis of titration curves to reveal differences between two types of hemoglobin identified as Hb fast and Hb slow. 2. Globins from Hb fast and Hb slow were purified by fast protein liquid chromatography (FPLC). Electrophoretic differences were found in the respective alpha-chains using polyacrylamide gel disc-electrophoresis at acid pH, polyacrylamide gel isoelectric focusing and by subsequently analyzing titration curves. 3. The results suggest that the alpha chains of Hb fast and Hb slow, called I alpha and II alpha, respectively, differ in at least two aminoacid residues. Subsequently, these amino acids were identified as lysine and cysteine.