enzyme

module not yet titled

restriction enzymes and restriction maps of plasmids

The future of genetic research

code for enzymes, the biological catalysts that do much of the body's

from the other parent produces enough of the enzyme to serve the body's

retina. The basic fault is an enzyme defect that causes an abnormal

an example, Valle points out that the human enzyme ornithine delta

identical to the comparable enzyme that functions in yeast.

Enzyme Kinetics Examples

Enzyme Kinetics Examples

Enzyme Kinetics Examples

[S] >> Km. The enzyme is saturated with substrate.

Measuring KM and Vmax

each enzyme. Once you have an assay for enzyme activity, you can determine

Use of DNA in Identification

By taking that DNA and cutting it with an enzyme that recognizes a

Solving Enzyme Structure Problems

Solving Enzyme Structure Problems

Solving Enzyme Structure Problems

The structure of the enzyme Tryptophan Synthetase has been studied extensively by a variety

In a series of studies, Yanofsky and co-workers examined the effect on enzyme activity of

inactive enzyme: the new amino acid side chain is charged instead of neutral; or the new amino acid's

and charged. However, the second data set shows that substituting valine, whose side chain is larger than glycine but uncharged, results in an inactive enzyme. This indicates that it is the size of the amino acid

Therefore, changing gly --> glu (M1) overfills the pocket, resulting in inactive enzyme. The effects of

formation of inactive enzyme. Therefore, the pocket has to be a certain size for the enzyme to function:

Examples of Viral Replication Pathways

enzyme cuts the host chromosome and integrates viral genes into it. When

3.3 Michaelis-Menten Kinetics

(a constant flux of S "through" the enzyme). Mathematically, this can

(the total enzyme is either bound to substrate or free)

7.01Recombinant DNA Practice Problem

inserted (don't alter the structure of b-galactosidase enzyme enough to

3 Proteins

specific enzymes that compose a cell's metabolism. An E. coli

Structure and Function of Organelles

digestive enzymes . Here we can see an advantage of the

support such destructive enzymes if they were not contained in a

7.012 Cloning Project: Agricultural Biotechnology

c) How would you clone the OA degrading enzyme genes

folate as a co-enzyme. Folate is a co-enzyme which is used to transfer

* translated ORF3 has regions similar to enzymes which carry out

utilization in these bacteria and the roles of the enzymes produced by

degrading enzymes should then degrade the OA like the bacteria do and

Hypertextbook Chapters

Enzyme Biochemistry

Lwoff's Pathways - Viral Replication

enzyme cuts the host chromosome and integrates viral genes into it. When

DNA Fingerprinting in Human Health and Society

Special enzymes called restriction enzymes are used to cut the DNA at

specific places. For example, an enzyme called EcoR1, found in

Enzyme Biochemistry Chapter

Enzyme Biochemistry Chapter

Enzyme Biochemistry Chapter

Enzyme Mechanisms

Enzyme Kinetics

3.2 Basic Enzyme Kinetics

3.5 Solving Enzyme Kinetics Problems

module not yet titled

the enzymes involved with DNA replication, RNA transcription, and protein translation

Cloning Genes

job. Our "scissors" are the class of enzymes called restriction

enzymes. There are well over a hundred restriction enzymes, each cutting

This segment is "glued" into place using an enzyme called DNA

Significance of Km and Vmax

Kd is a measure of how tightly the enzyme binds to the substrate

substrate for the enzyme.

enzyme as a function of [S].

"Vmax is a measure of how fast the enzyme can go at full speed."

Prokaryotic Gene Regulation

Beta-galactosidase is an enzyme that hydrolyses the sugar lactose (which is,

enzyme or no enzyme production at all.

Structural gene for lactose trans-acetylase protein. This enzyme

expression and enzyme levels will be high with and without lactose.

the yuckose operon. In the presence of yuckose, an enzyme, yuckase, is

MIT Biology Hypertextbook: Enzyme Mechanisms

MIT Biology Hypertextbook: Enzyme Mechanisms

2 Enzyme Mechanisms

Most biological enzymes are proteins . They perform the chemical

reactions in cells. Not all proteins are enzymes, but most enzymes are

product of that reaction. A substrate is a molecule upon which an enzyme

enzyme, but, for a favored reaction (where delta G is negative), the

enzyme can speed it up.

Enzymes Catalyze Reactions

Enzymes have affinity for the substrate in a transition state. They get

enzyme may increase the local concentration of the two substrates A and

The part of the enzyme that does the work is called the active site .

the enzyme's work.

Enzymes are named in a variety of ways. Several of the general rules of

enzyme nomenclature are listed below.

help you digest the food. (An enzyme with this function, produced by the

the enzyme might be an endonuclease or an exonuclease

Receptors

specialized enzyme domain that becomes activated whenever the

the case of many GF receptors, this cytoplasmic enzyme domain contains

Recall that kinases are enzymes that attach phosphate groups to

Solving Chemical Equilibrium Problems

enzyme hexokinase:

be phosphorylated by an enzyme called glucokinase. Glucokinase has a

According to the Michaelis-Menten model of enzyme kinetics, the fraction

of enzyme involved in ES complexes is:

Chemical Energetics

spontaneously, even with enzymes to catalyze it.

They are coupled (on an enzyme surface) into

enzymes!) The parts donated may be atoms or groups of atoms or, in some

3 Enzyme Kinetics

3 Enzyme Kinetics

3 Enzyme Kinetics

Assaying Enzymes

To study an enzyme, an assay is necessary. The assay is a measurement

used to assay (measure) enzyme activity more easily that the 'normal'

Enzyme catalysis

Here is an example of an enzyme catalyzed reaction:

The enzyme converts S to P (substrate to product). Initially, [P] is

reaction rate increases, until equilibrium is reached (enzymes catalyze

To measure the kinetic properties of a given enzyme, you must perform

many experiments like the one above. Keep the enzyme concentration

The more enzyme added, the faster the reaction goes

Why isn't the graph linear? As [S] gets large, the enzyme becomes

limiting - all enzyme molecules are 'busy' operating on the substrate

and the rate of reaction depends on the amount of enzyme, not the amount

of substrate.(And since the amount of enzyme used in this series of

3.4 Competitive and Noncompetitive Inhibition

There are 2 main types of reversible enzyme inhibition.

and Vo approaches Vmax. Vmax is unchanged because all of the enzyme molecules

The inhibitor binds to another site on the enzyme and inactivates the

enzyme molecule. This effectively reduces the [E]tot available for

the remaining active enzyme molecules are unaltered, Km is unchanged.

3.2 Basic Kinetics

E enzyme (b-galactosidase)

ES enzyme-substrate complex

[E]tot (the amount of enzyme added to the reaction) is known.

G Protein Receptors

nearby protein, the enzyme adenylate cyclase, which until this time has

the G protein, the adenylate cyclase enzyme gets activated and does its

After a several second encounter with the adenyl cyclase enzyme,

phosphorylate and thereby activate an enzyme that activates

Enzyme Biochemistry

Enzyme Biochemistry

molecular structure of enzymes (ie: primary, secondary, etc.)

activities of certain protein digesting enzymes

prosthetic groups commonly associated with enzymes

regulation of enzyme activity (reversible and irreversible inhibition)

competitive and non-competitive inhibition of enzymes

Polymerase Chain Reaction - Xeroxing DNA

enzymes to remain stable at high temperatures. No problem for Thermus

enzymes called polymerases make a copy of all the DNA in each

it started. So the cell has another enzyme called a primase that

nucleotide, the enzyme adds on a T nucleotide to the primer. If the template

Southerns, Northerns, Westerns, & Cloning: Molecular Searching Techniques

an enzyme. The location of this complex can then be used to get

DNA cut with restriction enzymes - probed with radioactive DNA.

DNA is first cut with restriction enzymes and the resulting

Sample 2 is what a sample of total DNA cut with a restriction enzyme,

plasmid is digested with particular restriction enzymes and the digest

radioactive. A set of enzymes catalyzes the following reaction:

Enzyme-conjugated Antibodies for Westerns

of an enzyme. The resulting antibody-enzyme conjugate is still able to

If an antibody-enzyme conjugate was used as a probe, this can be

enzyme. Usually, the substrate produces an insoluble colored product (a

chromogenic substrate) when acted upon by the enzyme. This produces a

with a restriction enzyme and run it on a Southern blot probed with a

Solving Problems

EcoRI+HindIII: Digestion with both enzymes will result in cleavage of

using: other restriction enzymes; a probe to exon 2 only; or even by

gene on a plasmid, from which you generate probes by restriction enzyme

3.5 Solving Enzyme Kinetics Problems

3.5 Solving Enzyme Kinetics Problems

3.5 Solving Enzyme Kinetics Problems

Vo, enzyme of A: Vo, enzyme of B: Faster

2) Given an enzyme with a Km = 10 mM and Vmax = 100 mmol/min.

a) With [S]>>KM, the enzyme is running close to Vmax . Because of

b) With [S] = Km, the enzyme is running at 50% of Vmax. Decreasing

3)The enzyme Carbonic Anhydrase (CA) catalyzes the following reaction:

a) Since the tubes are at equilibrium, and since enzymes do not

rapid absorption or production of CO2. Normally, enzyme assays are carried

equilibrium, so that the effect of adding enzyme will be detectable.}

4) The enzyme Lysozyme is present in human nasal mucus and catalyzes

units before the enzyme can get into the active conformation. This is an

Feedback Inhibition

A biosynthetic pathway is made up of a series of enzymes

biosynthetic pathway composed of four enzymes, labelled 1 through 4, that

an excess of E in the cell, E (or a byproduct of E) will inhibit enzyme