alpha, beta-Unsaturated and related amino acids in peptides and proteins.
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Biomedical subjects
Publications and source records attributed to E Gross.
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Serial liver enzyme and bilirubin concentrations were measured in 100 patients undergoing total parenteral nutrition. Between the eighth and tenth days, serum glutamic-pyruvic transaminase levels rose to 5.4 times pretotal parenteral nutrition levels; serum glutamic-oxalacetic transaminase, 2.8 times; bilirubin, 2.3 times, and lactic dehydrogenase, 1.5 times. These elevations were transient, lasting four to ten days. Biopsies of the liver taken during maximal elevations demonstrated marked periportal fatty change. A second elevation of serum glutamic-pyruvic transaminase, serum glutamic-oxalacetic transaminase, alkaline phosphatase and lactic dehydrogenase occurred in one-third to one-half of those patients receiving total parenteral nutrition for longer than a 20 day period. These elevations were more prolonged, and no biopsies were taken. Amino acid solutions contain conversion products of tryptophan, an amino acid that is unstable in the presence of the preservative sodium bisulfite which is added to all commercially available protein solutions. Infusion of these products into rats, either alone or as part of total parenteral nutrition solutions, resulted in periportal fatty change of the livers identical to that seen in our patients receiving total parenteral nutrition. A toxic effect of tryptophan conversion products in total parenteral nutrition solutions is proposed.
The single-channel conductance lambda and the mean channel lifetime gamma of natural and synthetic gramicidins A, B, and C has been studied. Significant differences in delta were found between gramicidin A and B; both gramicidins differ only in one amino acid (tryptophan replaced by phenylaline). The distribution of lambda is narrow in glycerylmonooleate membranes but considerably broader in dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine membranes. The ratio of the single-channel conductances in glycerylmonooleate and dioleoyl phosphatidylcholine membranes is only about two and is considerable smaller than the conductance ratio of nonactin-mediated cation transport. This finding suggests that dipolar potentials at the membrane/solution interface have little influence on the conductance of the gramicidin channel.
Substances from urinary extracts of normal, nonpregnant subjects and human pituitary gonadotropin preparations were found to react similarly to human chorionic gonadotropin (hCG) in a radioimmunoassay system that is highly specific for hCG and without crossreactivity to human luteinizing hormone (hLH). The antiserum was produced in a rabbit immunized with a bovine albumin conjugate of the unique carboxyl-terminal peptide (residues 123-145) isolated from a tryptic digest of the reduced, S-carboxymethylated hCGbeta subunit. The antibody recognition site on the peptide was found to reside on the last 15 amino acid residues of the carboxyl-terminal peptide, as evidenced by the competitive binding activities against 125I-labeled hCG of a series of peptides chemically synthesized according to the carboxyl-terminal sequence of HCGbeta. In order to elucidate the nature of the crossreacting substance in urinary extracts, a human postmenopausal urinary preparation (Pergonal) and a kaolin-acetone extract of urine from a patient with Klinefelter's syndrome were subjected to gel chromatography on Sephadex G-100. The results indicate that fractions showing immunocrossreactivity with the antiserum to hCGbeta-carboxyl-terminal peptide coeluted with 125I-labeled hCG which was separated distinctly from hLH. The same fractions from this postmenopausal urinary gonadotropin preparation exhibited in vitro biological activity proportional to the immunocrossreactivity of the hCG-specific antiserum. Concentration of postmenopausal women's urine by acetone precipitation retained approximately five times more immunoreactivity per unit volume than kaolin-acetone extraction, when assayed with the antiserum to hCGbeta-carboxyl-terminal peptide.
The first example of the premature termination of a polypeptide chain in man appears to be Hb McKees Rocks, beta145 Tyr leads to Term, discovered in polycythemic members of a Caucasian family. Point mutation has apparently occurred at the codon for Tyr beta145 from UAU to a "nonsense" codon, UAA or UAG, resulting in a shortened polypeptide chain with Lys 144 as its carboxyl-terminal amino acid. Evidence for this structural conclusion is the absence of tryptic peptide betaT-15 from "fingerprints" of the abnormal beta-chain, the finding of C-terminal Lys, and the similarity between the functional properties of this variant hemoglobin and those of des Tyr (145)-His(146)beta hemoglobin resulting from carboxypeptidase-A digestion of normal human hemoglobin. Hb McKees Rocks has markedly abnormal properties: its oxygen affinity is the highest of the human variants described to date; its Bohr effect is reduced; it is devoid of subunit cooperativity; and it is unaffected by 2,3-diphosphoglyceric acid. These properties are probably the consequences of decreased stability of the T quaternary conformation and are partially restored in the presence of the strong allosteric effector inositol hexaphosphate.
A case of primary leiomyosarcoma of the greater saphenous vein with metastatic spread to the thyroid gland and subcutaneous tissue is described. The literature of saphenous vein leiomyosarcomas is reviewed.
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