The active site and the substrate binding site of penicillinase (fl-lactamase) from Bacillus licheniformis were altered in this study so that the enzyme retains the specific binding capability to the fl-lactam antibiotics, but fails to hydrolyze them. When Lys47 in the enzyme molecule was replaced by Ala47, the mutant protein PenP(KA) lost not only its catalytic activity but also the substrate ...

The topological location of the nucleotide substrate binding environments on adenylate kinase has been explored with the fluorescent molecule [4-benzoyl]benzoyl-1-amidofluorescein (BzAF) and the nucleotide analog 3’-0-[4-benzoyl]benzoyl-ATP (BzATP), which a re site-directed photoaffinity probes that bind covalently at the individual nucleotide sites. The MgBzATP substituted for MgATP as a subs...

Phytochelatin synthase (PCS) uses the substrates glutathione (GSH, γGlu-Cys-Gly) and a cadmium (Cd)-bound GSH (Cd∙GS2) to produce the shortest phytochelatin product (PC2, (γGlu-Cys)2-Gly) through a ping-pong mechanism. The binding of the 2 substrates to the active site, particularly the second substrate binding site, is not well-understood. In this study, we generated a structural model of the ...

The multispecific efflux transporter, P-glycoprotein, plays an important role in drug disposition. Substrate translocation occurs along the interface of its transmembrane domains. The rotational C2 symmetry of ATP-binding cassette transporters implies the existence of two symmetry-related sets of substrate-interacting amino acids. These sets are identical in homodimeric transporters, and remain...

A Monte Carlo docking procedure that combines random displacements of the substrate and protein side chains with minimization of the enzyme]substrate complex is described and applied to finding the binding mode of the blocked tetrapeptide N-acetyl-Leu-Pro-Phe-methylamide to the FK506 binding protein Ž . FKBP . The tetrapeptide, an analog of the preferred FKBP substrate, and the FKBP binding sit...

Polyethylene glycol dehydrogenase (PEGDH) from Sphingopyxis terrae (formerly Sphingomonas terrae) is composed of 535 amino acid residues and one flavin adenine dinucleotide per monomer protein in a homodimeric structure. Its amino acid sequence shows 28.5 to 30.5% identity with glucose oxidases from Aspergillus niger and Penicillium amagasakiense. The ADP-binding site and the signature 1 and 2 ...

Background: DNA polymerases use a multistep mechanism to faithfully replicate DNA. Results: Replicative DNA polymerase PolB1 binds DNA in multiple conformations which are affected by nucleotide or mismatched DNA binding. Conclusion: Modulation of conformational dynamics and DNA binding kinetics affects the replication fidelity of PolB1. Significance: Single-molecule techniques can reveal subtle...

Copper amine oxidases are homodimeric enzymes containing one Cu(2+) ion and one 2,4,5-trihydroxyphenylalanine quinone (TPQ) per monomer. Previous studies with the copper amine oxidase from Escherichia coli (ECAO) have elucidated the structure of the active site and established the importance in catalysis of an active-site base, Asp-383. To explore the early interactions of substrate with enzyme...