Enzymes And Vitamins Flashcards
This is the process of chemical and physical change which goes on continually in the living organism
Metabolism
The acceleration of a chemical reaction by some substance which itself undergoes no permanent chemical change.
Catalysis
The catalysts of biochemical reactions are
Enzymes
are composed of long chains of amino acids that have folded into a very specific three-dimensional shape which contains an active site.
Enzymes
a region on the surface of an enzyme to which substrates will bind and catalyzes a chemical reaction.
Active site
a molecule that an enzyme reacts
Substrate
Enzymes have molecular weights ranging from
10,000 to 2,000,000
are macromolecules that catalyze chemical reactions in the body.
Enzymes
Enzymes catalyze reactions by weakening?
chemical bonds
Has a unique 3d shape
Enzymes
Each enzyme has a unique 3-D shape, including a surface groove called on
Active site
are enzymes made of ribonucleic acids.
Ribozymes
catalyzes only the hydrolysis of urea and not that of other amides, even closely related ones
Urease
an enzyme that cleaves the peptide bonds of protein molecules—but not every peptide bond, only those on the carboxyl side of lysine and arginine residues.
Trypsin
specifically catalyzes the hydrolysis of only the last amino acid on a protein chain-the one at the C-terminal end.
carboxypeptidase
They catalyze the hydrolysis of any triglyceride, but they still do not affect carbohydrates or proteins
Lipases
hydrolyzes the amino acid L-arginine (the naturally occurring form) to a compound called L-ornithine and urea but has no effect on its mirror image, D-arginine.
arginase
earliest studies were performed in 1835 by the Swedish chemist who termed their chemical action catalytic?
Jon Jakob Berzelius
earliest studies were performed in 1835 by the Swedish chemist Jon Jakob Berzelius who termed their?
chemical action catalytic
What year the first enzyme was obtained in pure form?
1926
In 1926, the first enzyme was obtained in pure form, a feat accomplished by?
James B. Sumner
He was able to isolate and crystallize the enzyme urease from the jack bean.
James B. Sumner
James B. Sumner work was to earn him the?
1947 Nobel Prize
- They discovered a complex procedure for isolating pepsin.
- Shared the 1947
Nobel Prize with Sumner.
John H. Northrop and Wendell M.
Stanley
speeds up the removal of hydrogen from lactate
lactate dehydrogenase
catalyzes the hydrolysis of phosphate ester bonds under acidic conditions.
Acid phosphatase
the names of most enzymes end in
-ase
Some enzymes, however, have older names, which were assigned before their actions were clearly understood. Among these are? ( all enzymes of the digestive tract. )
pepsin, trypsin, and chymotrypsin
catalyze oxidations and reductions
EC 1 - oxidoreductases
catalyze the transfer of a group of atoms, such as from one molecule to another
EC 2 - transferases
catalyze hydrolysis reactions
EC 3 - hydrolases
catalyze the addition of two groups to a double bond or the removal of two groups from adjacent atoms to create a double bond
EC 4 - lyases
catalyze isomerization reactions
EC 5 - isomerases
catalyze the joining of two molecules
EC 6 - ligases
an enzyme that oxidizes a substrate by transferring one or more hydrides (H-) to an acceptor, usually NAD+/NADP+ or a flavin coenzyme FAD or FMN.
Dehydrogenase
tricarboxylic acid cycle, (TCA cycle),
also called?
Krebs cycle and citric acid cycle
The second stage of cellular respiration. the three-stage process by which living cells break down organic fuel molecules in the presence of oxygen to harvest the energy they need to grow and divide.
tricarboxylic acid cycle, (TCA cycle)
An enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen (O2) as the electron acceptor.
Oxidase
An enzyme that catalyzes a type of reaction between an amino acid and alpha-keto acid.
Transaminase
an enzyme that transfers phosphate groups from high-energy molecules, such as ATP, to specific substrates.
Kinase
a water-soluble enzyme that catalyzes the hydrolysis of ester chemical bonds in water-soluble substrates. It helps your body digest fats.
Lipase
- an enzyme that breaks starch down into sugar.
- an enzyme, or special protein, that helps you digest carbohydrates
Amylase
an enzyme that catalyzes (increases reaction rate or “speeds up”) proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products.
Peptidase
enzymes that catalyze decarboxylation of amino acids, beta-keto acids, and alpha-keto acids.
Decarboxylases
an enzyme that catalyzes the structural rearrangement of isomers.
Isomerase
an enzyme that catalyzes the shifting/movement of a functional group from one position to another within the same molecule.
Mutase
Other enzymes contain nonprotein portions called?
cofactors
The protein (polypeptide) portion of the enzyme is called an?
apoenzyme
Organic cofactors are called
coenzymes
Enzyme along with its
cofactor?
Holoenzyme
When cofactor Is
Removed Enzyme is?
Apoenzyme
What vitamins are important group of coenzymes which are essential to the activity of many enzymes.
B vitamins
Another important coenzyme which is part of several oxidoreductases as well as part of hemoglobin.
heme
- The compound on which the enzyme works, and whose reaction it speeds up, is called the?
substrate
usually binds to the enzyme surface while it undergoes the reaction.
Substrate
The substrate binds to a specific portion of the enzyme during the reaction, called the?
active site
is any process that initiates or increases the action of an enzyme. It can be the simple addition of a cofactor to an apoenzyme or the cleavage of a polypeptide chain of a proenzyme.
Activation
A process that makes an active enzyme less active or inactive.
Inhibition
bind to the active site of the enzyme surface, thereby preventing the binding of substrate.
Competitive inhibitors
bind to some other portion of the enzyme surface and sufficiently alter the tertiary structure of the enzyme so that its catalytic effectiveness is eliminated. That is, the enzyme cannot catalyze while the inhibitor is bound.
Noncompetitive inhibitors
The nonprotein part of an enzyme necessary for its catalytic function.
Cofactor
A nonprotein organic molecule, frequently a B vitamin, that acts as a cofactor.
Coenzyme
A three-dimensional cavity of the enzyme with specific chemical properties that enable it to accommodate the substrate.
Active site
A compound that binds to an enzyme and lowers its activity.
Inhibitor
This person suggested that catalysts speed up reactions by combining with the substrate to form some kind of intermediate compound. In an enzyme- catalysed reaction, this intermediate is called the enzyme substrate complex.
Arrhenius
Arrhenius suggested that catalysts speed up reactions by combining with the substrate to form some kind of intermediate compound. In an enzyme- catalysed reaction, this intermediate is called the?
enzyme-substrate complex.
This model assumes that the enzyme is a rigid three-dimensional body.
The surface that contains the active site has a restricted opening into which only one kind of substrate can fit, just as only the proper key can fit exactly into a lock and turn it open.
lock-and-key model
A model explaining the specificity of enzyme action by comparing the active site to a lock and the substrate to a key.
Lock-and-key model
He introduced the induced-fit model,
Daniel Koshland
the changes occurring in the shape of the cavity upon substrate binding to the changes in the shape of a glove when a hand is inserted.
induced-fit model
forms covalent or very strong noncovalent bonds. The site of attack is an amino acid group that participates in the normal enzymatic reaction.
Irreversible inhibitor
forms weak, noncovalent bonds that readily dissociate from an enzyme. The enzyme is only inactive when the inhibitor is present.
Reversible inhibitor
A survey of known active sites of enzymes shows that five amino acids participate in the active sites in more than 65% of all cases. They are, in order of their dominance, what are those amino acids?
His > Cys > Asp > Arg > Glu
before A and B can become C and D, they must pass through a?
transition state
The energy required to climb this hill is the?
activation energy
is a protease, an enzyme that cleaves peptide bonds as we saw with trypsin.
papain
helps attract the peptide and hold it in the correct orientation via hydrogen bonding
histidine
The sulfur on the cysteine side chain performs a type of reaction called a?
nucleophilic attack
This enzyme catalyzes the transfer of the phosphate group from phosphoenolpyruvate (PEP) to ADP, an important step in glycolysis.
pyruvate kinase
Enzyme activity is regulated by five mechanisms:
• Feedback Control
• Proenzymes
• Allosterism
• Protein Modification
• Isoenzymes
• is an enzyme regulation process in which formation of a product inhibits an earlier reaction in the sequence.
• The reaction product of one enzyme may control the activity of another, especially in a complex system in which enzymes work cooperatively. For example, in such a system, each step is catalyzed by a different enzyme:
Feedback control
Some enzymes are manufactured by the body in an inactive form. To make them active, a small part of their polypeptide chain must be removed. These inactive forms of enzymes are called?
proenzymes
Proenzymes are also called?
Zymogens
a protein that becomes an active enzyme after undergoing a chemical change.
Proenzyme (zymogen)
Enzyme regulation based on an event occurring at a place other than the active site but that creates a change in the active site.
Allosterism
an enzyme regulated by allosterism mechanism is called an
allosteric enzyme
an enzyme in which the binding of a regulator on one site on the enzyme modifies the enzyme’s ability to bind the substrate in the active site.
Allosteric enzyme
The substance that binds to an allosteric enzyme is called a
regulator
the site to which regulator attaches is called a
regulatory site
The modulator, also called the? Can have a positive or negative effect on allosteric enzyme activity
regulator or effector
can have a postive or negative effect on allosteric enzyme activity
modulator
bind with an allosteric site on the enzyme and stabilize the ACTIVE conformation therefore speeding up the reaction rate.
Positive Modulators (activators)
bind to an allosteric site that stabilizes the INACTIVE conformation of the molecule therefore slowing the
reaction rate.
Negative Modulators (inhibitors)
Binding of a regulator to a site other than the active site changes the shape of the active site.
The allosteric effect
In allosterism this more active form is regulators are seen to function by active site changes the referred to as the
R form
R form, where “R” stands for?
relaxed
In allosterism the less active form is referred to as?
T form
T form, where “T” stands for?
taut
The modification is usually a change in the primary structure, typically by addition of a functional group covalently bound to the apoenzyme.
protein modification
Enzymes that catalyze such
phosphorylation go by the common name of
kinases
catalyzes the oxidation of lactate to pyruvate, and vice versa.
Lactate dehydrogenase (LDH)
Two kinds of subunits in isoenzymes, called?
H and M
The enzyme that dominates in the heart is an
H4 enzyme
In the liver and skeletal muscles, what type of subunit dominates?
M-type
Other types of tetramer combinations exist in different tissues:
H3M, H2M2 and HM3
Other types of tetramer combinations exist in different tissues:
H3M, H2M2, and HM3. These different forms of the same enzyme are called?
isozymes or isoenzymes
enzymes that perform the same function but have different combinations of subunits and thus different quaterary structures.
Isozymes (Isoenzymes)
LDH is used to convert lactate to? in the heart.
pyruvate
The M4 isozyme favors the production of?
lactate
The distribution of LDH isozymes can be seen using the technique of?
electrophoresis
The distribution of LDH isozymes can be seen using the technique of electrophoresis, where samples are separated in a gel using an?
electric field
a molecule that mimics the transition state of a chemical reaction and that is used as an inhibitor of an enzyme.
Transition-state analog
catalyzes a reaction that converts L-proline to D-proline.
Proline racemase
it has been over 50 years since the last of the known vitamins was discovered. What is the vitamin?
Vitamin B12
Solubility characteristics divide the vitamins into two major classes:
the water-soluble vitamins and the fat (lipid)-soluble vitamins.
must be constantly replenished in the body because they are rapidly eliminated from the body in the urine. They are carried in the bloodstream, are needed in frequent, small doses, and are unlikely to be toxic except when taken in unusually large doses.
Water-soluble vitamins
are found dissolved in lipid materials. They are, in general, carried in the blood by protein carriers, are stored in fat tissues, are needed in periodic doses, and are more likely to be toxic when consumed in excess of need.
The fat-soluble vitamins
Water-soluble vitamins function as?
coenzymes
has the simplest structure of the 13 vitamins
Vitamin C
Vitamin C, which has the simplest structure of the 13 vitamins, exists in two active forms in the human body:
an oxidized form and a reduced form
Vitamin C also functions as a? for water-soluble substances in the blood and other body fluids.
General antioxidant
Vitamin C’s biosynthesis involves?
L-gulonic acid
L-gulonic acid, an acid derivative of the monosaccharide?
L-gulose
An intake of what mg/day? of vitamin C saturates all body tissues with the compound.
100 mg/day
Vitamin B involves four topics:
nomenclature, function, structural characteristics, and dietary sources.
Water-soluble vitamins:
• Thiamin (vitamin B1)
• Riboflavin (vitamin B2)
• Niacin (nicotinic acid, nicotinamide, vitamin B3)
• Vitamin B6 (pyridoxine, pyridoxal, pyridoxamine)
• Folate (folic acid)
• Vitamin B12 (cobalamin)
• Pantothenic acid (vitamin B5)
• Biotin
• Vitamin C
Fat-solube vitamins
• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K
B vitamin structure is very diverse. The only common thread among structures is that all structures, except that of ? , involve heterocyclic nitrogen ring systems.
pantothenic acid
B vitamin structure is very diverse. The only common thread among structures is that all structures, except that of pantothenic acid, involve?
heterocyclic nitrogen ring systems
The element sulfur is present in two structures, what are those?
(thiamin and biotin) and B12
vitamin B12 contains a?
metal atom
have been linked positively to improvement in cardiovascular health.
niacin and folate
is the most effective treatment currently available to increase low levels of HDL
prescription niacin
Another study shows that younger women (26-46 years old) who consume 800 μg of folate per day reduce the risk of developing ? by almost a third compared to those who consume less than 200 μg/day
high blood pressure
Many of the functions of the fat-soluble vitamins involve processes that occur in?
cell membranes
Normal dietary intake provides a person with both ? forms of vitamin A
preformed and precursor
Preformed vitamin A forms are called?
retinoids
The retinoids include?
retinal, retinol, and retinoic acid
The major carotenoid with vitamin A activity is? which can be cleaved to yield two molecules of vitamin A.
beta-carotene
is a yellow to red-orange pigment plentiful in carrots, squash, cantaloupe, apricots, and other yellow vegetables and fruits, as well as in leafy green vegetables (where the yellow pigment is masked by green chlorophyll).
Beta-carotene
In the eye, vitamin A (as retinal) combines with the protein opsin to form the visual pigment rhodopsin.
Vision
participates in the conversion of light energy into nerve impulses that are sent to the brain.
Rhodopsin
is the process whereby immature cells change in structure and function to become specialized cells.
Regulating Cell Differentiation
covers outer body surfaces as well as lining internal cavities and tubes.
Epithelial tissue
Lack of vitamin A (as retinoic acid) causes such surfaces to become?
drier and harder than normal
In men, vitamin A participates in?
sperm development
In women, normal fetal development during pregnancy requires?
vitamin A
The two most important members of the vitamin D family of molecules are?
vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol)
is produced in the skin of humans and animals by the action of sunlight (ultraviolet light) on its precursor molecule,
Vitamin D3
It is produced from the plant sterol ergosterol through the action of light.
Vitamin D2 (ergocalciferol)
Both the cholecalciferol and the ergocalciferol forms of vitamin D must undergo two further hydroxylation steps before the vitamin D becomes fully functional. The first step, which occurs in the liver, adds a?
-OH group to carbon 25
Both the cholecalciferol and the ergocalciferol forms of vitamin D must undergo two further hydroxylation steps before the vitamin D becomes fully functional. The first step, which occurs in the liver, adds a -OH group to carbon 25. The second step, which occurs in the kidneys, adds a?
-OH group to carbon 1
The rest of the body’s vitamin D supplies are made within the body (skin) with the help of?
sunlight
triggers the deposition of calcium salts into the organic matrix of bones by activating the biosynthesis of calcium-binding proteins.
Vitamin D
There are four forms of vitamin E:
alpha-, beta-, delta-, and gamma-tocopherol.
The tocopherol form with the greatest biochemical activity is?
alpha-tocopherol
is the main form of vitamin E in vitamin-E rich foods.
Gamma-tocopherol
Plant oils (margarine, salad dressings, and shortenings), green and leafy vegetables, and whole-grain products are sources of?
vitamin E
Only a few foods, including liver, fatty fish (such as salmon), and egg yolks, are good natural sources of?
vitamin D
Foods derived from plants provide carotenoids, which serve as precursor forms of?
vitamin A
The primary function of vitamin E in the body is as?
antioxidant
a compound that protects other compounds from oxidation by being oxidized itself
antioxidant
is particularly important in preventing the oxidation of polyunsaturated fatty acids in membrane lipids.
Vitamin E
Vitamin E’s antioxidant action involves it giving up the hydrogen present on its ? group to oxygen-containing free radicals.
—OH
A most important location in the human body where vitamin E exerts its antioxidant effect is the? , where exposure of cells to oxygen (and air pollutants) is greatest.
lungs
cells that pass through the lungs, as well as the cells of the lung tissue itself, benefit from vitamin E’s protective effect.
red and white blood cells
Infants, particularly premature infants, do not have a lot of vitamin?
Vitamin E
is administered to the infant along with oxygen to give antioxidant protection.
vitamin E
Vitamin E has also been found to be involved in the conversion of ? to prostaglandins.
arachidonic acid (20:4)
is found in animals and humans and can be synthesized by bacteria, including those found in the human intestinal tract.
Vitamin K2
are the form of vitamin K found in vitamin K supplements.
Menaquinones
is essential to the blood-clotting process.
Vitamin K
is sometimes given to presurgical patients to ensure adequate prothrombin levels and prevent hemorrhaging.
Vitamin K
is also required for the biosynthesis of several other proteins found in the plasma, bone, and kidney.
Vitamin K
In 1969, He proposed that an immunogen (a molecule that elicits an antibody response) would elicit antibodies with catalytic activity if the immunogen mimicked the transition state properties (shape, charge) of the reaction.
William Jencks
They created the first catalytic antibodies
Richard Lerner and Peter Schultz
is a protein designed to bind to specific molecules on the immunogen
antibody
antibody is a protein designed to bind to specific molecules on the immunogen, the antibody will, in essence, serve as a?
fake active site
an antibody that has catalytic ability because it was created by using a transition-state analog as an immunogen.
Abzyme
an organic compound, essential in small amounts for the proper functioning of the human body that must be obtained from dietary sources because the body cannot synthesize it
Vitamin
The site of tremendous biochemical activity called metabolism.
Living cell
Enzymes are high molecular weight compounds made up principally of chains of amino acids linked together by
peptide bonds
Enzymes catalyze reactions by weakening chemical bonds, which lowers?
Activation energy
Another type of regulation of enzyme activity occurs when the same enzyme appears in different forms in different tissues.
Isoenzyme
a molecule that elicits an antibody response
immunogen
are considered in conjunction with enzymes
Vitamins
are often required for women during pregnancy and for people recovering from certain illnesses.
supplemental vitamins
manufactured in the laboratory, are identical to the vitamins found in foods.
synthetic vitamins
introduces a double bond into the ring, producing L-ascorbic acid.
oxidase
contain a higher concentration of vitamin C than any other organ in the body.
adrenal glands
B vitamins that have more than one form of the vitamin exists.
niacin and vitamin B6
must be chemically modified before they become functional within the coenzymes
B vitamins
Foods derived from animals, including egg yolks and dairy products, provide? that are easily hydrolyzed to retinoids in the intestine.
retinyl esters
Foods derived from plants provide?
carotenoids
Four major functions of Vitamin A in a body:
- Vision
- Regulating cell differentiation
- Maintenance of health of Epithelial tissues
- Reproduction and Growth
Vitamin K1, also called?
phylloquinone
Vitamin K2 has several forms, called?
menaquinones
has a side chain that is predominantly saturated; only one carbon-carbon double bond is present. It is a substance found in plants.
Vitamin K1
This vitamin side chains have several carbon-carbon double bonds, in contrast to the one carbon-carbon double bond present in phylloquinone.
Vitamin K2
