When Jensen sarcoma cells were cultured in medium devoid of free L-asparagine, the cell population decreased exponen tially for 10 days. The surviving cells then began an exponen ti@alproliferation phase. The resulting population did not quire asparagine to maintain proliferation. Population growth curves and cloning studies showed that, per 106 original cells, approximately 102 variant cells w...

BACKGROUND: A limited number of studies have investigated the inclusion of amino acids in calf starter. OBJECTIVES: This study was aimed to evaluate different levels of crude protein in starter and supplement- ing some protected amino acids on efficiency, health status and blood metabolites of dairy calves and to com- pare it with unprotected amino acids. <st...

Sequence segments of about 140 amino acids in length, each containing a selected consensus region, were used in alignments of the aminoacyl-tRNA synthetases with the aim of discerning their evolutionary relationships. In all cases tested, enzymes specific for the same amino acid from a variety of organisms grouped together, reinforcing the supposition that the aminoacyl-tRNA synthetases are ver...

Class IIa bacteriocins are heat-stable, unmodified peptides with a conserved amino acids sequence YGNGV on their N-terminal domains, and have received much attention due to their generally recognized as safe (GRAS) status, their high biological activity, and their excellent heat stability. They are promising and attractive agents that could function as biopreservatives in the food industry. Thi...

The addition of organic solvents to α-amino acids in aqueous solution could be an effective method in crystallization. We reviewed the available data on the solubility of α-amino acids in water, water-ethanol mixtures, and ethanol at 298.15 K and 0.1 MPa. The solubility of l-alanine, l-proline, l-arginine, l-cysteine, and l-lysine in water and ethanol mixtures and the solubility of l-alanine, l...

Background: In Africa, tuberculosis is generally regarded as persisting as one of the most devastating infectious diseases. The pediatric population is particularly vulnerable, with infection of the brain in the form of tuberculous meningitis (TBM) being the most severe manifestation. TBM is often difficult to diagnose in its early stages because of its non-specific clinical presentation. Of pa...

L-Asparagine auxotrophy in Saccharomyces cerevisiae is the result of mutation in each of two unlinked cistrons, ASN1 and ASN2. Mutation in only one of these cistrons yields growth indistinguishable from that of wild-type cells under a variety of nutritional stresses. Relatively high concentrations of L-asparagine are required to permit maximal growth of the auxotrophs, and the amino acid requir...

Urinary amino acids were determined in 162 individuals (62 young non-vegetarians, 24 elderly non-vegetarians, 40 young vegetarians and 36 elderly vegetarians) by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The two methods used in this study were compared. The difference in the percentage frequencies of detection by TLC and HPLC in non-vegetarian group was ...

The tryptophan-containing peptides were isolated from the chymotryptic digest of S-carboxymethylated papain. Residue 175, which is strongly hydrogen-bonded to the active-site histidine residue in the tertiary structure of papain, is asparagine, confirming the work of Kimmel, Rogers & Smith (1965). Its function is probably to maintain the orientation and tautomeric state of the imidazole ring of...

The base pairs in double helical nucleic acids have been compared to see how they can be recognized by proteins. We conclude that a single hydrogen bond is inadequate for uniquely identifying any particular base pair, as this leads to numerous degeneracies. However, using two hydrogen bonds, fidelity of base pair recognition may be achieved. We propose specific amino-acid side chain interaction...