Glucose-leucine system formation

Effect of humidity on volatile and color formation from a glucose-leucine system... 

Proximal tubule cells in culture should have retained functional attributes such as (1) polar architecture and junctional assembly of epithelia and correct membrane distribution of enzymes and transport systems (2) vectorial transport of solutes and water, manifested by the formation of domes when cultured on solid supports [81] and the generation of transepithelial electrophysiological properties [82, 83] due to the expression of proximal tubule specific claudins 2- and 10 [84, 85] (3) cellular uptake of xenobiotics from either the apical or basolateral side, as observed in vivo and (4) expression of nephron segment-specific characteristics, i.e., distinct expression of differentiation markers, metabolic and transport properties, and hormone responsiveness. Such markers include the expression of the brush border enzymes alkaline phosphatase, leucine aminopeptidase, and y-glutamyl transferase [4, 86], In addition, proximal tubule cells should possess Na+,K+-ATPase activities, Na+-dependent glucose, and p-aminohippurate transport. Proximal tubule cells increase cAMP levels in response to parathyroid... 

In contrast to the system of Shimura et al. (1964), intact protoplasts of strain 10716 require six amino acids for production of bacitracin and, for maximal yield, glucose is needed. Disrupted protoplasts are unable to synthesize the antibiotic (Snoke, 1961). With protoplasts, the six needed amino acids are L-cysteine, L-isoleucine, L-leucine, L-histidine, L-ornithine, and L-asparagine. Neither D-orni-thine nor D-asparagine can be utihzed directly and D-phenylalanine inhibits formation of bacitracin in the absence of L-phenylalanine. A peptide factor in soybean was found to be stimulatory for synthesis of bacitracin by whole cells provided that D-phenylalanine is present in the reaction mixture (Snoke, i960, 1961). In the absence of the D-amino acid, the peptide factor is inactive. 

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