Related Experiment Video
Updated: Jun 15, 2026

Defining Substrate Specificities for Lipase and Phospholipase Candidates
Published on: November 23, 2016
Substrate specificity and evolutionary implications of a NifDK enzyme carrying NifB-co at its active site
Basem Soboh1, Eric S Boyd, Dehua Zhao
1Institute of Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle, Germany.
Abstract:
The in vitro reconstitution of molybdenum nitrogenase was manipulated to generate a chimeric enzyme in which the active site iron-molybdenum cofactor (FeMo-co) is replaced by NifB-co. The NifDK/NifB-co enzyme was unable to reduce N(2) to NH(3), while exhibiting residual C(2)H(4) and considerable H(2) production activities. Production of H(2) by NifDK/NifB-co was stimulated by N(2) and was dependent on NifH and ATP hydrolysis. Thus, NifDK/NifB-co is a useful tool to gain insights into the catalytic mechanism of nitrogenase. Furthermore, phylogenetic analysis of D and K homologs indicates that several early emerging lineages, which contain NifB, NifH and NifDK encoding genes but which lack other genes required for processing NifB-co into FeMo-co, might encode an enzyme with similar catalytic properties to NifDK/NifB-co.
Related Concept Videos
Induced-fit Model
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Introduction to Mechanisms of Enzyme Catalysis
Enzymes
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Nucleophiles
Role of Reduced Coenzymes NADH and FADH₂
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...

