Biochemical and structural characterization of Cryptosporidium parvum Lactate dehydrogenase

Abstract

The protozoan parasite Cryptosporidium parvum causes waterborne diseases worldwide. There is no effective therapy for C. parvum infection. The parasite depends mainly on glycolysis for energy production. Lactate dehydrogenase is a major regulator of glycolysis. This paper describes the biochemical characterization of C. parvum lactate dehydrogenase and high resolution crystal structures of the apo-enzyme and four ternary complexes. The ternary complexes capture the enzyme bound to NAD/NADH or its 3-acetylpyridine analog in the cofactor binding pocket, while the substrate binding site is occupied by one of the following ligands: lactate, pyruvate or oxamate. The results reveal distinctive features of the parasitic enzyme. For example, C. parvum lactate dehydrogenase prefers the acetylpyridine analog of NADH as a cofactor. Moreover, it is slightly less sensitive to gossypol inhibition compared with mammalian lactate dehydrogenases and not inhibited by excess pyruvate. The active site loop and the antigenic loop in C. parvum lactate dehydrogenase are considerably different from those in the human counterpart. Structural features and enzymatic properties of C. parvum lactate dehydrogenase are similar to enzymes from related parasites. Structural comparison with malate dehydrogenase supports a common ancestry for the two genes.

Novel lactate dehydrogenase inhibitors with in vivo efficacy against Cryptosporidium parvum

“…At amino acid sequence level, CpLDH is only 25% identical to human LDH, with the active site conformation of CpLDH being significantly different from that of the human LDH [24]. Further, in the 3-dimensional structure model of the two enzymes, the helix-loop portion of CpLDH is more proximal to the active site loop than it is in the human LDH [24].…”

A mechanistic kinetic description of lactate dehydrogenase elucidating cancer diagnosis and inhibitor evaluation

“…LDH, as an interactive tetrameric enzyme, follows the general mechanistic kinetic principles expressed above. In studies conducted to examine the substrate (pyruvate or lactate) effect on LDH kinetic activities, an excess of coenzyme (NAD + or NADH) is generally added to saturate and fully activate the enzyme 20 , 21 . Based on the reaction mechanism ( Figure 3 ) and Equation (1) to (6) , the reaction rate can be expressed as …”

Molecular cloing and bioinformatics analysis of lactate dehydrogenase from Taenia multiceps

“…In parasites, LDH can catalyze reversible reactions between pyruvic acid and lactic acid with the concomitant oxidation of NADH to NAD + (Cook et al 2014 ), thus helping parasites use energy (Ramljak et al 2015 ). If LDH is inhibited, the development and growth of parasites will cease or they may die (Veerakumari and Munuswamy 2000 ).…”