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Results for “Amino Acids, Basic”

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At least 289 records · Page 16Linked to original sources
PubMed1985

Endopeptidase in human cerebrospinal fluid which cleaves proenkephalin B opioid peptides at consecutive basic amino acids.

An endopeptidase releasing the common N-terminal hexapeptide, (Leu)-enkephalin-Arg6, from dynorphins A and B, and alpha-neoendorphin was purified from human cerebrospinal fluid. Purification involved ion-exchange chromatography (DEAE-Sepharose CL-6B), hydrophobic interaction chromatography (phenyl-Sepharose CL-4B) and molecular sieving (Sephadex G-100). The enzyme showed molecular heterogeneity. A major fraction had an apparent molecular weight of about 40,000. It had an optimum activity in the pH range of 6-8. The conversion of dynorphin A was not affected by EDTA or iodoacetate but strongly reduced in the presence of phenylmethyl-sulphonyl fluoride, suggesting the enzyme is a serine protease.

Amino Acids↗
PubMed1992

Effect of dietary excess-histidine on fructose 1,6-bisphosphatase and 6-phosphofructokinase activities, and activation of fructose 1,6-bisphosphatase by basic amino acids in rat liver.

1. Dietary excess histidine caused an increase in the total activity of fructose 1,6-bisphosphatase, and a decrease in 6-phosphofructokinase in the liver. 2. The hepatic concentrations of free histidine and lysine were higher in rats fed a histidine-excess diet. 3. The addition of histidine, lysine or arginine to the assay mixture for fructose 1,6-bisphosphatase resulted in a significant increase in its activity. The 6-phosphofructokinase activity in the liver was not enhanced by the addition of histidine to the assay mixture.

Amino Acids↗
PubMed1992

Uptake of basic amino acids and peptides into liposomes in response to transmembrane pH gradients.

The uptake of derivatives of lysine and a pentapeptide (ala-met-leu-trp-ala) into large unilamellar vesicle (LUV) systems in response to transmembrane pH gradients has been examined. In these derivatives, the C-terminal carboxyl functions have been converted to methyl esters or amides. It is shown that the presence of a pH gradient (interior acidic) results in the rapid and efficient accumulation of these weak base amino acid and peptide derivatives into LUVs in a manner consistent with permeation of the neutral (deprotonated) form. It is suggested that this property may have general implications for mechanisms of transbilayer translocation of peptides, such as signal sequences, which exhibit weak base characteristics.

Amino Acid Sequence↗