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Degradation of Dynorphin-Related Peptides by the Puromycin-Sensitive Aminopeptidase and Aminopeptidase M 总被引:1,自引:0,他引:1
Abstract: The degradation of dynorphin-related peptides by the puromycin-sensitive aminopeptidase and aminopeptidase M was examined using these peptides as alternate substrate inhibitors. K i determinations showed that both aminopeptidases exhibit a higher affinity for longer dynorphin-related peptides, i.e., K i for dynorphin A-17 = 23–30 n M with the K i increasing to 25–50 µ M for the enkephalin pentapeptides. Binding appears dependent not only on peptide length, but also on its sequence. With aminopeptidase M, as the peptide size increases from five to 10 amino acids, k cat remains relatively constant; however, as the peptide size increases beyond a decapeptide, k cat decreases significantly. With the puromycin-sensitive aminopeptidase, similar results were obtained except that k cat was greatest for the pentapeptide. Thus, if one considers k cat / K m as the relevant kinetic constant for estimating in vivo peptide hydrolysis, these results are consistent with the involvement of aminopeptidase M and the puromycin-sensitive aminopeptidase in the degradation of extended dynorphin-related peptides. 相似文献
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