A reaction happens need the energy to vibrate the molecules and the reactant concentration enough. The energy here is often provided by heat.
However, in living system, high temperature may harm the biological structure
Truly that the concentration in living system is very low. So living organisms solve these problems by using enzyme
Trace element (iron, manganese, cobalt, copper, zinc, selenium, and molybdenum): chemical element that is needed in minute quantities for the proper growth, development, and physiology of the organism.
In biochemistry, a trace element is also referred to as a micronutrient.
Although the chemical nature of the catalytic mechanism of the serine pro-tease a-chymotrypsin (a-CT) is largely understood, the influence of the
enzyme’s structural dynamics on its catalysis remains uncertain. Here we
investigate whether a-CT’s structural dynamics directly influence the kinet-ics of enzyme catalysis.
Enzyme catalysis in low water containing organic solvents is
finding an increasing number of applications in diverse
areas.This review focuses on some aspects which have not
been reviewed elsewhere.Different strategies for obtaining
higher activity and stability in such media are described.In
this context, the damaging role of lyophilization and the
means of overcoming such effects are discussed.Ultrasoni-cation and microwave assistance are two emerging approa-ches for enhancing reaction rates in low water media.
Recent years have witnessed high levels of activity in identifying enzyme systems that catalyse H-transfer by quantum tunneling. Rather than being restricted to a small number of speciﬁc enzymes as perceived initially, it has now become an accepted mechanism for H-transfer in a growing number of enzymes. Furthermore, H-tunneling is driven by the thermally induced dynamics of the enzyme. In some of those enzymes that break stable C–H bonds the reaction proceeds purely by quantum tunneling, without the need to partially ascend the barrier.
Snake venoms are cocktails of enzymes and non-enzymatic proteins used
for both the immobilization and digestion of prey. The most common
snake venom enzymes include acetylcholinesterases, L-amino acid oxidases,
serine proteinases, metalloproteinases and phospholipases A2
Metabolism ofD-amino acids is of considerable interest due to their key
importance in cell structure and function. Salmonella typhimuriumD-serine
deaminase (StDSD) is a pyridoxal 5¢ phosphate (PLP) dependent enzyme that
catalyses degradation of D-Ser to pyruvate and ammonia.
The relative contributions to the specificity and catalysis of aglycone, of
residues E190, E194, K201 and M453 that form the aglycone-binding site
of ab-glycosidase from Spodoptera frugiperda(EC 126.96.36.199), were investi-gated through site-directed mutagenesis and enzyme kinetic experiments.
The 3C-like protease of the severe acute respiratory syndrome (SARS) cor-onavirus has a C-terminal extra domain in addition to the chymotrypsin-fold adopted by piconavirus 3C proteases hosting the complete catalytic
machinery. Previously we identified the extra domain to be involved in
enzyme dimerization which has been considered essential for the catalytic
(BQ) Part 1 book "Lehninger principles of biochemistry" presents the following contents: The foundations of biochemistry, structure and catalysis (water, amino acids, peptides, and proteins; the three dimensional structure of proteins, protein function, enzymes, carbohydrates and glycobiology, carbohydrates and glycobiology).
International Tables for Crystallography, Volume F, Crystal-
lography of Biological Macromolecules, was commissioned by
the International Union of Crystallography (IUCr) in recognition
of the extraordinary contributions that knowledge of macro-
molecular structure has made, and will make, to the analysis of
biological systems, from enzyme catalysis to the workings of a
Aminotransferases catalyse synthetic and degradative reactions of amino
acids, and serve as a key linkage between central carbon and nitrogen
metabolism in most organisms. In this study, three aminotransferases (AT1,
AT2 and AT3) were purified and characterized fromHydrogenobacter
thermophilus, a hydrogen-oxidizing chemolithoautotrophic bacterium, which
has been reported to possess unique features in its carbon and nitrogen
A common feature of all the proposed mechanisms for monoamine oxidase
is the initiation of catalysis with the deprotonated form of the amine sub-strate in the enzyme–substrate complex. However, recent steady-state
kinetic studies on the pH dependence of monoamine oxidase led to the sug-gestion that it is the protonated form of the amine substrate that binds to
Family 18 chitinases such as chitinase B (ChiB) fromSerratia marcescens
catalyze glycoside hydrolysis via a mechanism involving the N-acetyl group
of the sugar bound to the)1 subsite. We have studied the degradation of
the soluble heteropolymer chitosan, to obtain further insight into catalysis
in ChiB and to experimentally assess the proposed processive action of this
enzyme. Degradation of chitosans with varying degrees of acetylation was
monitored by following the size-distribution of oligomers, and oligomers
were isolated and partly sequenced using
The X-ray structure of the diol dehydratase–adeninylpentylcobalamin com-plex revealed that the adenine moiety of adenosylcobalamin is anchored in
the adenine-binding pocket of the enzyme by hydrogen bonding of N3
with the side chain OH group of Sera224, and of 6-NH2, N1 and N7 with
main chain amide groups of other residues.
His334 facilitates catalysis byCorynebacterium callunaestarch phosphory-lase through selective stabilization of the transition state of the reaction,
partly derived from a hydrogen bond between its side chain and the C-6
hydroxy group of the glucosyl residue undergoing transfer to and from
hort hydrogen bonds are present in many chemical and biological sys-tems. It is well known that these short hydrogen bonds are found in the
active site of enzymes and aid enzyme catalysis. This study aims to system-atically characterize all short hydrogen bonds from a nonredundant dataset
of protein structures. The study has revealed that short hydrogen bonds
are commonly found in proteins and are widely present in different regions
of the protein chain, such as the backbone or side chain, and in different
secondary structural regions such as helices, strands and turns. ...
c-Glutamyltranspeptidase (GGT; EC 188.8.131.52), an enzyme found in organ-isms from bacteria to mammals and plants, plays a central role in glutathi-one metabolism. Structural studies of GGTs from Escherichia coliand
Helicobacter pylori have revealed detailed molecular mechanisms of
catalysis and maturation.
Mutants of a cobalt-containing nitrile hydratase (NHase,
EC 184.108.40.206) fromPseudonocardia thermophilaJCM 3095
involved in substrate binding, catalysis and formation of the
active center were constructed, and their characteristics and
crystal structures were investigated. As expected fromthe
structure of the substrate binding pocket, the wild-type
enzyme showed significantly lower KmandKi values for
aromatic substrates and inhibitors, respectively, than alipha-ticones.