Open AccessActive‐Site‐Directed Inhibition of the Plasma‐Membrane Carrier Transporting Short‐Chain, Neutral Amino Acids into Trypanosoma brucei
Author(s) -
OWEN Michael J.,
VOORHEIS H. Paul
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10197.x
Subject(s) - amino acid , trypanosoma brucei , active transport , glycine , serine , biochemistry , active site , chemistry , facilitated diffusion , membrane transport , carrier system , stereochemistry , membrane , enzyme , telecommunications , computer science , gene
1 Glycine chloromethyl ketone inhibited the active‐transport of l ‐serine into bloodstream forms of Trypanosoma brucei . 2 Substrates of the short‐chain, neutral amino acid transport system (N 1 ), but not of other amino acid transport systems, protected the carrier protein from inhibition. 3 Inhibition was never more than 80% complete. The residual activity might have due to a pro‐portion of N1 carrier active sites which had not reacted with the inhibitor. 4 The inhibition was highly selective for the N, amino acid transport system. Other amino acid transport systems were not affected and the rate of respiration was only slightly affected. 5 The inhibition was first‐order with respect to concentration, indicating that one molecule of the inhibitor reacted with each carrier activesite. 6 The high selectivity of this inhibitor should make it a useful labelling agent during the isolation and purification of the N 1 amino acid transport carrier protein(s).