Enrique F Velázquez-Contreras

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Enzymatic activity is dependent on temperature, although some proteins have evolved to retain activity at low temperatures at the expense of stability. Cold adapted enzymes are present in a variety of organisms and there is ample interest in their structure-function relationships. Lysozyme (E.C. is one of the most studied enzymes due to its(More)
Thymidylate synthase (TS) catalyzes the synthesis of deoxythymidine monophosphate (dTMP), which is an essential precursor for DNA synthesis. The rationale underlying drug design is to identify compounds that differentially inhibit a viral or parasite enzyme vs. the host homologue. We studied the TS of the white spot syndrome virus (WSSV TS) and the(More)
Biosynthesis of nucleoside triphosphates is critical for bioenergetics and nucleic acid replication, and this is achieved by nucleoside diphosphate kinase (NDK). As an emerging biological model and the global importance of shrimp culture, we have addressed the study of the Pacific whiteleg shrimp (Litopenaeus vannamei) NDK. We demonstrated its activity and(More)
The compounds 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza-17,40-dioxa[]paracyclophane and 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza[]paracyclophane binuclear copper complexes (Cu2PO and Cu2PC, respectively) were studied by determining their antioxidant capacity(More)
Nucleotide phosphorylation is a key step in DNA replication and viral infections, since suitable levels of nucleotide triphosphates pool are required for this process. Deoxythymidine monophosphate (dTMP) is produced either by de novo or salvage pathways, which is further phosphorylated to deoxythymidine triphosphate (dTTP). Thymidyne monophosphate kinase(More)
Thymidylate synthase (TS) catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) using methylene tetrahydrofolate (CH(2)THF) as cofactor, the glutamate tail of which forms a water-mediated hydrogen bond with an invariant lysine residue of this enzyme. To understand the role of this interaction, we studied the K48Q mutant of Escherichia(More)
The cyclophanes 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10, 24,27,30,33-octaaza-17,40-dioxa[]paracyclophane (PO) and 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza[]paracyclophane (PC) were coordinated with iron to form cationic binuclear Fe(III) Fe₂PO and Fe₂PC complexes, respectively.(More)
Arginine kinase (AK) is a key enzyme for energetic balance in invertebrates. Although AK is a well-studied system that provides fast energy to invertebrates using the phosphagen phospho-arginine, the structural details on the AK-arginine binary complex interaction remain unclear. Herein, we determined two crystal structures of the Pacific whiteleg shrimp(More)
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