In earlier reports from this laboratory, a series of new synthetic substrates for pepsin was described.'-' These compounds are of the general type Z-His-X-YOAI\e4 where X and Y are the residues of amino acids such as L-phenylalanine, p-nitro-L-phenylalanine, L-tyrosine, L-tryptophan, and L-leucine; the enzymic action is limited to the cleavage of the X-Y bond. One of the substrate analogues pre...

tively. In the presence of aprotinin, simple inhibition of the reaction did not occur, since a plot of 1 / v against \ I 1 did not give a straight line relationship, whereas a plot of l / v against 111" did, indicating that there is more than one binding site for the kininogenase (Dixon & Webb, 1964). Plots were linear when n = 2 at low substrate concentrations (S-2266, 0 . 0 2 m ~ : Bz-Arg-OEt...

LeuT serves as the model protein for understanding the relationships between structure, mechanism and pharmacology in neurotransmitter sodium symporters (NSSs). At the present time, however, there is a vigorous debate over whether there is a single high-affinity substrate site (S1) located at the original, crystallographically determined substrate site or whether there are two high-affinity sub...

because of participation in many aspects of human life, and due to oxidation-sensitive characteristics of dopamine (da) and arachidonoyl dopamine (aa-da), the necessity of biocompatible carrier to keep them against oxidation is of importance. in this work, we explored the putative binding sites of da and aa-da to -lactoglobulin (blg) as potent carrier. docking results identified the binding si...

Eukaryotic neurotransmitter:sodium symporters (NSSs), targets for antidepressants and psychostimulants, terminate neurotransmission by sodium-driven reuptake. The crystal structure of LeuT(Aa), a prokaryotic NSS homolog, revealed an occluded state in which one leucine and two Na(+) ions are bound, but provided limited clues to the molecular mechanism of transport. Using steered molecular dynami...

The Neurotransmitter:Sodium Symporters (NSSs) represent an important class of proteins mediating sodium-dependent uptake of neurotransmitters from the extracellular space. The substrate binding stoichiometry of the bacterial NSS protein, LeuT, and thus the principal transport mechanism, has been heavily debated. Here we used solid state NMR to specifically characterize the bound leucine ligand ...

Human paraoxonase (HuPON1) is a serum enzyme that exhibits a broad spectrum of hydrolytic activities, including the hydrolysis of various organophosphates, esters, and recently identified lactone substrates. Despite intensive site-directed mutagenesis and other biological studies, the structural basis for the specificity of substrate interactions of HuPON1 remains elusive. In this study, we app...

Insulin-degrading enzyme (IDE) exists primarily as a dimer being unique among the zinc metalloproteases in that it exhibits allosteric kinetics with small synthetic peptide substrates. In addition the IDE reaction rate is increased by small peptides that bind to a distal site within the substrate binding site. We have generated mixed dimers of IDE in which one or both subunits contain mutations...

LeuT is a member of the neurotransmitter/sodium symporter family, which includes the neuronal transporters for serotonin, norepinephrine, and dopamine. The original crystal structure of LeuT shows a primary leucine-binding site at the center of the protein. LeuT is inhibited by different classes of antidepressants that act as potent inhibitors of the serotonin transporter. The newly determined ...