Protein content of 60 mesh, dehydrated, defatted black gram (Phaseolus mungo) meal was 28.5%. Sodium carbonate (0.5-1.0%), t e tmsodium pyrophosphate (0.5%), and sodium dodecyl sulfate (0.5-5%) extracted more than 76 gram Lowry's protein per 100 gram Kjeldahl protein. On the considerations of contaminating residue in the final product and disruption o f native structure of the proteins these chemical agents were unsuitable. Sodium sulfate at 10% level was judged to be the best protein solubilizer. The phenol-acetic acidmercaptoethanol-urea (PAMU) system in polyacrylamide gel electrophoresis was more efficient in resolving protein subunits than the sodium dodecyl sulfate (SDS) gel system. PAMU dissociated total black gram proteins in one major and 7-8 other sharp bands. Proteins separated on PAMU gel were run on the f l a t bed polyacrylamide gel containing SDS system. The proteins were then separated in 13 subunits, the molecular weight o f the major one was 55,000. Defatting with n-hexane improved protein extraction by 6%. Solubilized proteins contained 81% globulins, 13% albumins, 4% ethanol soluble proteins, and 2% acetic acid soluble proteins.
Fermentation of black gram and rice blend was investigated for the microbiological, physicochemical, and biochemical changes. Total soluble solids, soluble nitrogen, and soluble acids increased during fermentation whereas soluble sugars were decreased. Trypsin inhibiting activity was unaffected although chymotrypsin inhibiting activity was progressively reduced during fermentation process. Amino acid contents of the batter were increased with the increase in fermentation time with the exceptions of isoleucine and cysteine. Increase in methionine content was 60 and 420%, respectively a t 20 and 45 h fermentation. Enzymic digestion with pepsin and pan creatin indicated improuem en t in the availability of essential amino acids during the fermentation. Fermentation, thus, appeared to improue the nutritional quality o f the proteins in the black gram and rice blend.
The protein fractions, albumins, globulins, prolamins and glutelins, of black gram (PhaseoZus mungo L.) seeds were characterized for their amino acid compositions, isoelectric points, and subunit constitutions Globulins which formed 81% of the solubilized proteins were devoid of sulfur containing amino acids. Sulfur containing amino acids and threonine were deficient in total proteins of the seeds with 27.6 and 78.8 as their respective amino acid scores. Chemical scores of albumin, globulin, prolamin, and glutelin fractions were 64, 0, 56 and 70.7 respectively. The predicted biological values in human nutrition varied from 0 for globulins to 110 for glutelins and it was 14.9 for total proteins in the seeds. Dissolution of globulins was minimum ln a pH range, 5.3-5.9. Isoelectric focusing in a dissociating medium indicated that the majority of globulin subunits were acidic. Globulins, however, had two basic subunits with isoelectric points at 8.42 and 8.65. Two dimensional slab gel electrophoresis, with a phenol-acetic acid-mercaptoethanol-urea (PAMU) system in the first dimension and sodium dodecyl sulfate (SDS) system in the second dimension suggested that the mobilities of proteins in PAMU and SDS systems were based on the related parameters
A trypsin inhibitor isolated from black gram (Phaseolus mungo L.) had 75 amino acid residues with an estimated molecular weight of 7892. The kinetic constants Km and Vmax as evaluated by the Dixon and Cornish‐Bowden plots were 2.7 × 10−5and 6 × 10−3M/min, respectively. The dissociation constants of the enzyme‐inhibitor complex (Ki) and the enzyme‐inhibitor‐substrate complex (Ki') were respectively 4 × 10−7M and 1.9 × 10−6M. Trypsin inhibition by black gram trypsin inhibitor was of a linear‐mixed type. Chemical modification studies suggested the possible involvement of lysine and arginine at the active site of the inhibitor.
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