Val 70, Phe 72 and the last seven amino acid residues of C-terminal are essential to the function of norepinephrine transporter

The norepinephrine transporter(NET) is a member of the Na+/Cl- dependent neurotransmitter transporter family and constitutes the target of several clinically important antidepressants. To delineate the critical amino acid residues and the function of C-terminal in regulating transport activity of NET, here we constructed two site mutants (V70F, F72V; V70I, F72V) and one C-terminal truncated mutant (△611-617). The wild type and mutants of NET were expressed in Xenopus oocytes by injection of their cRNA. We found that all of these mutants lost their transport activity. These results indicate that the amino acid residues of V70 and F72 3 and the last seven amino acids of C-terminal are essential to the transport activity of NET.

肽类甜味剂的结构与甜味的关系

本文通过对氨基酸的结构与甜味的分析，并以Ａｓｐａｒｔａｍｅ为例，讨论了肽异构体Ｎ—端氨基酸，Ｃ—端氨基酸的结构对甜味的影响，对肽类甜味剂与甜味的关系进行小结，并提出了合成甜味剂的最新进展。