Isozymes of alpha-amylase in the porcine pancreas: population distribution.

1. Three isozymes of pancreatic alpha-amylase, PPA 1, PPA 2, and PPA 3, were observed in a porcine population of 50 animals. 2. Isozyme PPA 2 was common to each pancreas. 3. Three phenotypic patterns were described as: (A) consisting of PPA 2 alone (20%); (B) consisting of PPA 1 and PPA 2 (78%); and (C) consisting of all three forms (2%). 4. Amylase isozymes were separated by anion exchange chromatography using DE53. 5. Individual isozymes corresponded to one of the three isozymes found in pancreatin. 6. Individual isozymes were inhibited equally by an amylase inhibitor from wheat. 7. Differences in amylase isozymes were attributed to genetically controlled mechanisms and not to artifacts of isolation.

Automated assay of alpha-amylase inhibitor proteins by continuous flow analysis.

A procedure for the automated assay of purified amylase inhibitors was developed. Samples were analyzed at a rate of 60/h using ferricyanide reagent to monitor the suppression of the release of reducing groups from a solution of starch by a calibrated alpha-amylase reagent. In addition to the sequential analysis of individual samples, the use of gradients permitted the continuous analysis of the effect of substrate and of inhibitor concentration. Also described are some of the effects of starch and inhibitor concentration and time of preincubation on the amylase-inhibitor reaction. The procedure was also suitable for the assay of samples of amylase and should be applicable to the determination of the effects of inhibitors on other enzymes which release reducing sugars.

Population distribution of human salivary amylases: differential inhibition by wheat protein.

Based upon response to an inhibitor from wheat gliadin, 80 random samples of human salivary amylase were separated into three phenotypic groups. Each phenotype occurred with a high frequency rendering this a polymorphinc locus. The susceptibility to the inhibitor may be a useful marker for studies of tendency to caries and periodontal disease as well as for studies of genetic variation and linkage.

Anserine and carnosine in chicks (Gallus gallus) rat pups (Rattus rattus) and ducklings (Anas platyrhynchos): comparative ontogenetic observations.

1. Muscle and brain from developing chick embryos, as well as from day-old chicks, rats, and ducks were analyzed for the histidine-containing dipeptides, anserine and carnosine. 2. Anserine was found in the brain of all species studied, whereas in muscle, anserine was found only in chicks. 3. At 15 days, the muscle of developing chick embryo contained 41 +/- 9 mumoles/100 g anserine while carnosine was present at a level of less than 3 mumoles/100 g. 4. In day-old chicks the anserine level in muscle was 100 +/- 35 mumoles/100 g while the carnosine level was 22.5 +/- 1 mumoles/100 g. 5. These findings cast doubt on earlier hypotheses relating anserine and carnosine to muscle activity.

Terminal residues of hog pancreatic amylase.

Studies on the identification of the terminal residues in protease-free hog pancreatic alpha-amylase, prepared by glycogen precipitation, demonstrated the absence of free amino terminals when four different chemical procedures were used. These methods were based on reaction with fluorodinitrobenzene, trinitrobenzenesulfonic acid, dansyl chloride, and cyanate. In the search for the presence of a possible alpha-N-blocking group, an acetyl group was detected as acetic acid dinitrophenyl hydrazide after hydrazinolysis and dinitrophenylation. Quantitation of acetyl groups by a gas chromatographic or a specific enzymatic method yielded 0.7 mol of acetyl group per 51,000 g of protein. Other acyl groups, such as formyl or propionyl, were not found. Leucine was shown to be the carboxyl terminal residue by hydrazinolysis or by carboxypeptidase A digestion of acid denatured amylase. With either procedure, 0.8 mol of carboxyl terminal leucine was found per 51,000 g of protein. These findings are consistent with the proposal that hog pancreatic alpha-amylase is composed of a single, alpha-N-acetylated chain of molecular weight 50,000. Claims of other investigators for subunit and multichain structures for this enzyme are discussed in view of these end group data.

Purification and properties of peroxidase from Nitrosomonas europaea.

Peroxidase from the obligate chemosynthetic bacterium Nitrosomonas europaea was purified 1,500-fold, and its properties were examined. The enzyme had a molecular weight of 53,000 and exhibited characteristic absorption maxima at 410, 524, and 558 mmu. The optimal pH and temperature were 7.5 and 44 C, respectively. The peroxidase reaction had an energy of activation of 5,850 cal/mole and required a primary substrate (H(2)O(2)) concentration of 7 x 10(-6)m to proceed at half maximal velocity (K(m)). Reduced cytochrome, c,p-phenylenediamine and pyrogallol acted as hydrogen donors to the purified peroxidase-H(2)O(2) complex. Conditions most suitable for the chemical oxidation of ammonium by H(2)O(2) were determined. The reaction was rapid and produced nitrite but no nitrate. Hydroxylamine was not detected as an intermediate, but it could substitute for ammonium in the system. Neither the rate nor the extent of these reactions was influenced by purified peroxidase, and no evidence was obtained to support a conclusion that the enzyme performs a vital role in the transformation of ammonium to nitrite by N. europaea.