The enzymatic hydrolysis of cellulose encounters various limitations that
are both substrate- and enzyme-related. Although the crystallinity of pure
cellulosic Avicel plays a major role in determining the rate of hydrolysis by
cellulases from Trichoderma reesei, we show that it stays constant during
enzymatic conversion. The mode of action of cellulases was investigated by
studying their kinetics on cellulose samples.
Enzyme Nomenclature and Classification
• Enzymes are commonly named by adding a suffix "-ase" to the root name of the substrate molecule it is acting upon. For example, Lipase catalyzes the hydrolysis of a lipid triglyceride. Sucrase catalyzes
Nowadays, it is well known, a number of enzymes derived from a variety of different plants and microorganisms has been reported to 3.000. Among these, many of them p lay an important role in many practical applications, especially, hydrolases, in the food-processing for producing functional food of high quality. Enzymes seem to have a promising future. There is a presentation of some enzymes have successful application in the food-processing. The productivity (A%) of spare protein hydrolysis, catalyzed by papain has been calculated: for Scenedesmus = 64.0; for Spirulina = 52.
Less than 20 years ago the field of cannabis and the cannabinoids was still considered
a minor, somewhat quaint, area of research. A few groups were active in
the field, but it was already being viewed as stagnating. The chemistry of cannabis
was well known, Δ9-tetrahydrocannabinol (Δ9-THC), identified in 1964, being the
only major psychoactive constituent and cannabidiol, which is not psychoactive,
possibly contributing to some of the effects. These cannabinoids and several synthetic
analogs had been thoroughly investigated for their pharmacological effects.
Human serum paraoxonase 1 (HuPON1; EC 184.108.40.206) is a calcium-depend-ent six-foldb-propeller enzyme that has been shown to hydrolyze an array
of substrates, including organophosphorus (OP) chemical warfare nerve
agents. Although recent efforts utilizing site-directed mutagenesis have
demonstrated specific residues (such as Phe222 and His115) to be import-
The functional and structural significance of the C-terminal region ofBacil-lus licheniformis chitinase was explored using C-terminal truncation muta-genesis. Comparative studies between full-length and truncated mutant
molecules included initial rate kinetics, fluorescence and CD spectrometric
properties, substrate binding and hydrolysis abilities, thermostability, and
The crystalline polymorphic form of cellulose (cellulose Ia-rich) of the
green alga,Cladophora, was converted into cellulose III
I and Ib by super-critical ammonium and hydrothermal treatments, respectively, and the
hydrolytic rate and the adsorption of Trichoderma viridecellobiohydro-lase I (Cel7A) on these products were evaluated by a novel analysis based
on the surface density of the enzyme.
Onconase, a member of the ribonuclease superfamily, is a
potent cytotoxicagent that isundergoingphase II/IIIhuman
clinical trials as an antitumor drug. Native onconase from
Rana pipiensand its amphibian homologs have an N-ter-minal pyroglutamyl residue that is essential for obtaining
fully active enzymes with their full potential as cytotoxins.
When expressed cytosolically in bacteria, Onconase is
isolated with an additional methionyl (Met1) residue and
glutaminyl insteadof a pyroglutamyl residue at position 1 of
the N-terminus and is consequently inactivated....
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 purpose of this work was to study protein and lipid recovery from yellowfin tuna head by enzymatic hydrolysis as well as to analyse the amino acid compositions in tuna head protein hydrolysate and the fatty acid compositions in tuna head oil.
The 1,3(4)-b-d-glucanases of glycoside hydrolase family 16 provide useful
examples of versatile yet specific protein–carbohydrate interactions. In the
present study, we report the X-ray structures of the 1,3(4)-b-d-glucanase
Phanerochaete chrysosporiumLaminarinase 16A in complex withb-glucan
products from laminarin (1.6 A˚ ) and lichenin (1.1 A
) hydrolysis. The
G6G3G3G glucan, in complex with the enzyme, showed ab-1,6 branch in
the acceptor site.
The reuteransucrase enzymes ofLactobacillus reuteristrain 121 (GTFA)
andL. reuteristrain ATCC 55730 (GTFO) convert sucrose into a-d-glu-cans (labelled reuterans) with mainlya-(1fi4) glucosidic linkages (50% and
70%, respectively), plusa-(1fi6) linkages. In the present study, we report a
detailed analysis of various hybrid GTFA⁄O enzymes, resulting in the iden-
Formylglycine-generating enzyme (FGE) catalyzes in newly synthesized sul-fatases the oxidation of a specific cysteine residue to formylglycine, which
is the catalytic residue required for sulfate ester hydrolysis. This post-trans-lational modification occurs in the endoplasmic reticulum (ER), and is an
essential step in the biogenesis of this enzyme family.
Diadenosine polyphosphates (ApnAs) act as extracellular
signaling molecules in a broad variety of tissues. They were
shown to be hydrolyzed by surface-located enzymes in an
asymmetric manner, generating AMP and Apn-1 from
ApnA. The molecular identity of the enzymes responsible
remains unclear.We analyzed the potential ofNPP1, NPP2,
and NPP3, the three members of the ecto-nucleotide pyro-phosphatase/phosphodiesterase family, to hydrolyze the
diadenosine polyphosphates diadenosine 5¢,5¢¢¢-P
Methionine adenosyltransferase (MAT, EC 220.127.116.11)-medi-ated synthesis ofS-adenosylmethionine (AdoMet) is a two-step process consistingof the formation of AdoMet and the
subsequent cleavage of the tripolyphosphate (PPPi
)mole-cule, a reaction induced, in turn, by AdoMet. The fact that
the two activities, AdoMet synthesis and tripolyphosphate
hydrolysis, can be measured separately is particularly useful
when the site-directed mutagenesis approach is used to
determine the functional role of the amino acid residues
involved in each....
Ceramide is a lipid second messenger that acts on mul-tiple-target enzymes, some of which are involved in other
signal-transduction systems. We have previously demon-strated that endogenous ceramide modifies the metabolism
of brain ethanolamine plasmalogens. The mechanism
involved was studied. On the basis of measurements of
breakdown products, specific inhibitor effects, and previ-ous findings, we suggest that a plasmalogen-selective
phospholipase A2 is the ceramide target.
Penicillin acylase catalyses the hydrolysis and synthesis of
semisyntheticb-lactam antibiotics via formation of a cova-lent acyl-enzyme intermediate. The kinetic and mechanistic
aspects of these reactions were studied. Stopped-flow
experiments with the penicillin and ampicillin analogues
2-nitro-5-phenylacetoxy-benzoic acid (NIPAOB) and
D-2-nitro-5-[(phenylglycyl)amino]-benzoic acid (NIPGB)
showed that the rate-limiting step in the conversion of
penicillin G and ampicillin is the formation of the acyl-enzyme....
CTP synthase catalyzes the reaction glutamine + UTP
+ATPfiglutamate + CTP + ADP + Pi.The rate
of the reaction is greatly enhanced by the allosteric activator
GTP.We have studied the glutaminase half-reactionofCTP
synthase from Lactococcus lactisand its response to the
allosteric activator GTP and nucleotides that bind to
the active site. In contrast to what has been found for the
Escherichia colienzyme, GTP activation of the L. lactis
enzyme did not result in similarkcat
values for the glutami-nase activity and glutamine hydrolysis coupled to CTP
After studying this chapter, you should be able to accomplish the following outcomes: State and apply two energy laws to energy transformations, give reasons why ATP is called the energy currency in cells, give examples to show how ATP hydrolysis is coupled to energy-requiring reactions, describe a metabolic pathway and how they function,...
Lipases (triacylglycerol acylhydrolases, E.C. 18.104.22.168) are ubiquitous enzymes of consid-
erable physiological significance and industrial potential. Lipases catalyze the hydrolysis of
triacylglycerols to glycerol and free fatty acids. In contrast to esterases, lipases are activated
only when adsorbed to an oil–water interface (Martinelle et al., 1995) and do not hydrolyze
dissolved substrates in the bulk fluid. A true lipase will split emulsified esters of glycerine
and long-chain fatty acids such as triolein and tripalmitin. Lipases are serine hydrolases.