Crystallization is one of the most ancient and interdisciplinary topics of research known to mankind. Crystals can be organic or inorganic and may be produced from melts, liquid solutions, vapors or even in solid state. Notwithstanding its inherently high complexity, the crystallization process is part of our everyday lives, from ice making in our homes to the most state-of-the-art chemical and electronic industry.
A complex of chagasin, a protein inhibitor fromTrypanosoma cruzi, and
papain, a classic family C1 cysteine protease, has been crystallized. Kinetic
studies revealed that inactivation of papain by chagasin is very fast
), and results in the formation of a very tight,
reversible complex (Ki =36pm), with similar or better rate and equilib-rium constants than those for cathepsins L and B.
This textbook has evolved from part of the first-year graduate curriculum in the
Department of Materials Science and Engineering at the Massachusetts Institute of
Technology (MIT) . This curriculum includes four required semester-long subjects-
“Materials at Equilibrium,” “Mechanical Properties of Materials,” “Electrical, Optical,
and Magnetic Properties of Materials,” and “Kinetic Processes in Materials.
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
The enzymatic kinetics of glycoside hydrolase family 7 cellobiohydrolase
(Cel7A) towards highly crystalline celluloses at the solid–liquid interface
was evaluated by applying the novel concept of surface density (q) of the
enzyme, which is defined as the amount of adsorbed enzyme divided by the
maximum amount of adsorbed enzyme.
Kinetic experiments with a substrate series of phenylacetyl-arylamides reveal that at least one polar group in the amine
moiety is required for the proper orientation of the substrate
in the large nucleophile-binding subsite of penicillin acylase
ofEscherichia coli. Quantum mechanical molecular model-ling of enzyme–substrate interactions in the enzyme active
site shows that in the case of substrates lacking local sym-metry, the productive binding implies two nonsymmetrical
arrangements with respect to the two positively charged
guanidinium residues of ArgA145 and ArgB263....
The aim of the study was to investigate the crystallization kinetics and solidification
behaviour of Fe60Co8Mo5Zr10W2B15 bulk glass forming alloy. The solidification
behaviour in near-equilibrium and non-equilibrium cooling conditions was studied.
The eutectic and peritectic reactions were found to exist in the solidification
sequence of the alloy. The bulk metallic glass formation was achieved by using two
methods: quenching from the liquid state and quenching from the semi-state.
Candida albicansexo-b-1,3-glucanase (Exg; EC 184.108.40.206) is implicated in
cell wall b-d-glucan remodelling through its glucosyl hydrolase and⁄or
transglucosylase activities. A pair of antiparallel phenylalanyl residues
(F144 and F258) flank the entrance to the active site pocket. Various Exg
mutants were studied using steady-state kinetics and crystallography aiming
to understand the roles played by these residues in positioning the b-1,3-d-glucan substrate.
The geneyfdUfrom Escherichia coliencodes a putative oxalyl coenzyme A
decarboxylase, a thiamine diphosphate-dependent enzyme that is potentially
involved in the degradation of oxalate. The enzyme has been purified to
homogeneity. The kinetic constants for conversion of the substrate oxalyl
coenzyme A by the enzyme in the absence and presence of the inhibitor
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 220.127.116.11), were investi-gated through site-directed mutagenesis and enzyme kinetic experiments.
Neuronal PAS domain protein 2 (NPAS2) is a circadian rhythm-associated
transcription factor with two heme-binding sites on two PAS domains. In
the present study, we compared the optical absorption spectra, resonance
Raman spectra, heme-binding kinetics and DNA-binding characteristics of
the isolated fragment containing the N-terminal basic helix–loop–helix
(bHLH) of the first PAS (PAS-A) domain of NPAS2 with those of the
PAS-A domain alone.
Glucokinase (GK) is the central player in glucose-stimulated insulin release
from pancreatic b-cells, and catalytic activation by a-D-glucose binding has
a key regulatory function. Whereas the mechanism of this activation is well
understood, on the basis of crystal structures of human GK, there are no
similar structural data on ATP binding to the ligand-free enzyme and how
it affects its conformation.
The hyperthermostable chitinase from the hyperthermophilic archaeon
Pyrococcus furiosushas a unique multidomain structure containing two chi-tin-binding domains and two catalytic domains, and exhibits strong crystal-line chitin hydrolyzing activity at high temperature.
Many protein substrates of caspases are cleaved at noncanonical sites in
comparison to the recognition motifs reported for the three caspase sub-groups. To provide insight into the specificity and aid in the design of
drugs to control cell death, crystal structures of caspase-7 were determined
in complexes with six peptide analogs (Ac-DMQD-Cho, Ac-DQMD-Cho,
Ac-DNLD-Cho, Ac-IEPD-Cho, Ac-ESMD-Cho, Ac-WEHD-Cho) that
span the major recognition motifs of the three subgroups.
The effects of tyramine, serotonin and benzalkonium on the esterase and
aryl acylamidase activities of wild-type human butyrylcholinesterase and its
peripheral anionic site mutant, D70G, were investigated. The kinetic study
was carried out under steady-state conditions with neutral and positively
charged aryl acylamides.
Group I introns catalyze the self-splicing reaction, and their derived ribo-zymes are frequently used as model systems for the study of RNA folding
and catalysis, as well as for the development of non-native catalytic
Eight phospholipases A2 (PLAs) and four three-finger-toxins (3FTx) from
the pooled venom of Bungarus fasciatus(Bf) were previously studied and
sequenced, but their expression pattern in individual Bf venom and possible
geographic variations remained to be investigated. We herein analyze the
individual venom of two Bf specimens from Kolkata (designated as KBf)
to address this question.
The NS2B–NS3 protease complex is essential for the replication of dengue
virus, which is the etiologic agent of dengue and hemorrhagic fevers, dis-eases that are a burden for the tropical and subtropical areas of the world.
The active form of the NS3 protease linked to the 40 residues of the NS2B
cofactor shows highly flexible and disordered region(s)...
Highly active, small-molecule furin inhibitors are attractive drug candidates
to fend off bacterial exotoxins and viral infection. Based on the 22-residue,
active Lys fragment of the mung bean trypsin inhibitor, a series of furin
inhibitors were designed and synthesized, and their inhibitory activity
towards furin and kexin was evaluated using enzyme kinetic analysis.