PubMed Health⌕ Search

Biomedical subjects

E T Mertz

Publications and source records attributed to E T Mertz.

9 recordsLinked to original sources
PubMed1987

In vitro digestibility and amino acid composition of pearl millet (Pennisetum typhoides) and other cereals.

The purpose of this study was to compare in vitro digestibility, protein distribution patterns, and amino acid composition of pearl millet with other major cereals. Digestibility values for the pearl millet varieties were higher than that of sorghum and comparable to that of maize. In contrast to sorghum, digestibility of pearl millet and maize did not decrease significantly upon cooking. Protein distribution patterns of uncooked pearl millet and shifts in the different fractions as a result of cooking also resembled that of maize and not sorghum. The amino acid profile of pearl millet is more favorable than that of normal sorghum and normal maize and is comparable to the small grains, wheat, barley, and rice. On the basis of these findings, it appears that pearl millet is a nutritious and well-digested source of calories and proteins for humans.

Amino Acids↗
PubMed1986

Digestibility and utilization of protein and energy from Nasha, a traditional Sudanese fermented sorghum weaning food.

Whole grain sorghum flour was fermented into Nasha, a traditional Sudanese food, and freeze-dried or drum-dried. It was cooked and fed to convalescent malnourished infants and small children as 61% of total diet calories and all of 6.4% protein calories, with (Lys+) and without lysine supplementation to 3% of protein. Apparent absorptions of nitrogen were 73 +/- 5 and 74 +/- 6% of intake, significantly (P less than 0.01) less than those from preceding (Cas-1, 86 +/- 3%) and following (Cas-2, 85 +/- 3%) isonitrogenous casein diets. Apparent retentions of nitrogen from Nasha (26 +/- 10%) were significantly lower than those from Lys + (34 +/- 9%, P less than 0.05), Cas-1 (35 +/- 11%, P less than 0.01) or Cas-2 (49 +/- 9%, P less than 0.01). Retentions from Cas-2 were higher than those from Cas-1 or Lys + (P less than 0.01). Fecal wet and dry weights were higher (P less than 0.02) during both Nasha diets and Cas-2 than during Cas-1. Fecal energy and carbohydrate were significantly (P less than 0.01) higher from either Nasha diet than from either casein diet; fecal fat was not different. Two children received drum-dried Nasha without further cooking; digestibilities were not different from those of the cooked product but biological value was much lower. When properly cooked and consumed along with small amounts of a good source of lysine, Nasha is a satisfactory weaning food.

Absorption↗
PubMed1979

Plasmin-mediated proteolysis of casein in bovine milk.

Plasminogen was found to be present in bovine milk by crossreactivity between rabbit antiserum to plasminogen and casein prepared from milk by acid precipitation. This result was further supported by recovery of intact 125I-labeled plasminogen from rabbit milk after its intravenous injection. Freshly isolated whole bovine casein was observed to undergo slow autoproteolysis at 37 degrees C. Polyacrylamide gel electrophoresis revealed gradual disappearance of major caseins accompanied by appearance and increase in intensity of numerous electrophoretic bands. This autoproteolysis was inhibited by low concentrations of epsilon-aminocaproic acid (0.1 mM) and diisopropyl fluorophosphate (1 mM); catalytic amounts of urokinase accelerated the process. Autoproteolysis of isolated bovine beta-casein was shown by both urea and sodium dodecyl sulfate gel electrophoresis to result in formation of gamma 1- and gamma 2-caseins. Similar electrophoretic bands were formed when beta-casein was degraded by plasmin prepared from bovine blood serum. These results support the hypothesis that bovine plasmin occurs in milk and is identical to alkaline milk protease.

Animals↗
PubMed1978

Methods for improving cereal protein quality.

Three methods for improving cereal protein quality are discussed. Two older methods are supplementation with limiting essential amino acids and with protein concentrates high in those amino acids. The most recent method (since 1964) is the replacement of the normal cereal grain with its high lysine mutant counterpart. Three high lysine cereals are now available, corn, barley, and sorghum. In animal feeding, least cost formulas will determine which of the three improvement methods will be used. In human nutrition, cost, availability, palatability and acceptance are all equally important factors. In animals, pounds of gain per pound of feed will be the final measure of cereal protein quality. In humans, especially preschool children, the most important criterion will be the ability of the improved cereal protein to build a strong immune defense system. Animal studies show that protein quality is more important than calories when calories are restricted to less than ad libitum consumption. It is therefore essential that children restricted in their total energy intake have the best cereal protein quality possible to protect their immune system.

Age Factors↗
PubMed1977

Kinetic evidence for an intermediate in the deacetylation of monoacetyl-chymotrypsin.

Mono[14C]acetyl-chymotrypsin was prepared by treating alpha-chymotrypsin with a 10-fold molar excess of p-nitrophenyl[14C]acetate at pH 5, and the acetylated enzyme was isolated free of excess reagents by gel filtration. Deacetylation at pH 6.0 was followed by observing the decrease in acid-precipitable radioactivity and provided a first-order rate constant of 0.02 +/- 0.008 min-1. Reactivation of the acetylated protein was followed by continuously monitoring the appearance of esterolytic activity towards alpha-N-acetyltyrosine ethyl ester. Reactivation at pH 6.0 occurred exponentially with a first-order rate constant of 0.2 +/- 0.015 min-1, the reactivated enzyme exhibiting an apparent catalytic contant (k' cat) of 1200 +/- 60 min-1, which decreased to a value of 945 +/- 15 min-1 by an apparent first-order process with a rate constant of 0.025 +/- 0.006 min-1. These results are interpreted in terms of a two-step deacetylation of monoacetyl-chymotrypsin involving an acetylated intermediate with esterase activity.

Acetates↗
PubMed1976

Protein quality of two varieties of high-lysine maize fed alone and with black beans or milk to normal and depleted weanling rats.

Opaque-2 corn, modified high-lysine corn with vitreous endosperm, and common corn were compared in rat growth studies. Corn alone supplied 8.6% protein; and at both 8.6 and 11.4% protein, corn furnished 60% of the protein and either milk or black beans supplied 40%. The modified corn, which also was high in both lysine and tryptophan, did not differ significantly from Opaque-2 corn in its ability to stimulate growth and nitrogen deposition in both well-nourished and partially protein-depleted rats; and both were significantly superior to common corn when fed alone. Milk was a more effective supplement for corn than black beans, especially when high-lysine varieties were fed, whereas beans exerted a similar effect on all varieties of corn. The depleted rats deposited more nitrogen as a result of eating most diets than did well nourished rats. Implications of these findings for preschool children are discussed.

Amino Acids, Essential↗