Enzymes are proteins that catalyze chemical reactions. A protein is simply a polypeptide
composed of amino acids linked by a peptide bond, and the term generally, but
not always, refers to the folded conformation. To understand how an enzyme functions,
including its binding and functional properties, it is necessary to know the
properties of the amino acids and how the amino acids are linked together, including
the torsion angles of the bonds and the space occupied, and the interactions of the
atoms leading to the final conformations of the folded protein.
The book is intended to provide a sound basis for enzyme reactor design based on kinetic principles, and give an updated vision of the potentials and limitations of enzyme biocatalysis, especially with respect to recent applications in processes of organic synthesis. The book is structured in the form of a textbook that goes from basic principles of enzyme structure and function to reactor design for homogeneous systems with soluble enzymes, and heterogeneous systems with insolubilized enzymes.
We live in the age of biology—the human and many other organisms’
genomes have been sequenced and we are starting to understand the
function of the metabolic machinery responsible for life on our planet.
Thousands of new genes have been discovered, many of these coding for
enzymes of yet unknown function. Understanding the kinetic behavior
of an enzyme provides clues to its possible physiological role. From
a biotechnological point of view, knowledge of the catalytic properties
of an enzyme is required for the design of immobilized enzyme-based
In the four years since the first edition of Enzymes was published, I have been
delighted to learn of the wide acceptance of the book throughout the biochemical
community, and particularly in the pharmaceutical community. During this
time a number of colleagues have contacted me to express their views on the
value of the text, and importantly to make suggestions for improvements to the
content and presentation of some concepts. I have used the first edition as a
teaching supplement for a course in which I lecture at the University of
Pennsylvania School of...
Living processes consists almost entirely of biochemical
reactions. Without catalysts these reactions would not occur fast
enough to sustain life.How does an enzyme
------ because enzyme
is a catalytic protein-a
chemical agent that
changes the rate of a
reaction without being
consumed by the
Alter the appearance, aroma, texture and flavor of a product.
Deliver nutrients more effectively to the body or to make a food that is
difficult to digest a bit easier to swallow.
Accelerate the good fermentation time, giving a finished product in weeks
instead of months.
Many enzymes are added to grain feeds
in order to convert some of the
indigestible carbohydrates acting only as
dietary fiber to accessible energy
AMYLASES and GLYCASES (i.e.
xylanase, cellulase, galactanase,
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
- Polysaccharides are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
- Some polysaccharides serve as storage material, hydrolyzed as needed to provide sugar for cells.
- Other polysaccharides serve as building material for structures that protect the cell or the whole organism.
- The architecture and function of a polysaccharide are determined by its sugar monomers and by the positions of its glycosidic linkages.
PLANT CELLS, UNLIKE ANIMAL CELLS, are surrounded by a relatively thin but mechanically strong cell wall. This wall consists of a complex mixture of polysaccharides and other polymers that are secreted by the cell and are assembled into an organized network linked together by both covalent and noncovalent bonds. Plant cell walls also contain structural proteins, enzymes, phenolic polymers, and other materials that modify the wall’s physical and chemical characteristics.
Phản ứng enzyme hoạt động thủy phân minh họa bằng các protease serine là một trong nhiều loại trái phiếu chia tách và phản ứng hình thành liên kết xúc tác bởi các enzyme. Từ các nghiên cứu sớm nhất của các protein này, các nhà khoa học đã cố gắng phân loại chúng bởi tính chất của phản ứng mà họ cung cấp. Tên nhóm đã được giao cho các enzym chia sẻ reactivities phổ biế
Các hoạt động của một enzyme có thể bị chặn trong một số cách khác nhau. Ví dụ, các phân tử ức chế có thể liên kết với các trang web trên các enzyme gây trở ngại cho doanh thu thích hợp. Chúng tôi gặp phải những khái niệm chất nền và ức chế sản phẩm
Những nghiên cứu này cho thấy, trong số những thứ khác, tăng gấp đôi-lô đối ứng cổ điển được sử dụng để phân biệt loại thuốc ức chế đối với các chất ức chế enzyme đơn giản thất bại trong trường hợp các chất ức chế chặt chẽ ràng buộc. Ví dụ, dựa trên chỉ làm việc được trích dẫn bởi Morrison và các đồng nghiệp,
We purified two hatching enzymes, namely high choriolytic enzyme (HCE;
EC 188.8.131.52) and low choriolytic enzyme (LCE; EC 184.108.40.206), from the
hatching liquid ofFundulus heteroclitus, which were named FundulusHCE
(FHCE) and FundulusLCE (FLCE). FHCE swelled the inner layer of egg
envelope, and FLCE completely digested the FHCE-swollen envelope.
c-Glutamyltranspeptidase (GGT; EC 220.127.116.11), 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.
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
A novel plant protein isolated from the underground bulbs of
Scadoxus multiflorus, xylanase and a-amylase inhibitor protein (XAIP),
inhibits two structurally and functionally unrelated enzymes: xylanase and
a-amylase. The mature protein contains 272 amino acid residues which
show sequence identities of 48% to the plant chitinase hevamine and 36%
to xylanase inhibitor protein-I, a double-headed inhibitor of GH10 and
The active site of triosephosphate isomerase (TIM, EC: 18.104.22.168), a
dimeric enzyme, lies very close to the subunit interface. Attempts to
engineer monomeric enzymes have yielded well-folded proteins with dra-matically reduced activity.
Bacterial l-asparaginases are enzymes that catalyze the hydrolysis of
l-asparagine to aspartic acid. For the past 30 years, these enzymes have
been used as therapeutic agents in the treatment of acute childhood
Somatic angiotensin-converting enzyme (ACE) contains two homologous
domains, each bearing a functional active site. Studies on the selectivity of
these ACE domains towards either substrates or inhibitors have mostly
relied on the use of mutants or isolated domains of ACE.