Biochemistry - Ch 07 - Physiological Activity Of Proteins (Vocab)

Front 1

Define:

Allosteric Interaction

Back 1

The binding of ligand at one site in a macromolecule that affects the binding of other ligands at other sites in the molecule.

See also cooperative binding

Front 2

Define:

Bohr Effect

Back 2

The decreasing O₂ binding affinity of hemoglobin in response to a decrease in pH

Front 3

Define:

Cooperative binding

Back 3

A situation in which the binding of a ligand at one site on a macromolecule affect the affinity of other sites for the same ligand.

Both negative and positive cooperativity occur.

See also allosteric interaction.

Front 4

Define:

Heme

Back 4

A porphyrin derivative whose central Fe(II) atom is the site of reversible oxygen binding (in myoglobin and hemoglobin) or oxidation-reduction (in cytochromes).

Front 5

Define:

Hill Equation

Back 5

A mathematical expression for the degree of saturation of ligand binding to a molecule with multiple binding sites as a function of the ligand concentration.

Front 6

Define:

Hyperbolic Curve

Back 6

The graphical representation of the mathematical equation that describes the noncooperative binding of a ligand to a molecule or the rate of reaction catalyzed by a Michealis-Menten (who???) enzyme

Front 7

Define:

Ligand

Back 7

(1) A small molecule that binds to a larger molecule.

(2) A molecule or ion bound to a metal ion.

Front 8

Define:

Microfilament

Back 8

A 70-Å-diameter cytoskeletal element composed of actin.

Front 9

Define:

Myofibril

Back 9

The bundle of fibers that are arranged in register in striated muscle cells

Front 10

Define:

Noncooperative binding

Back 10

A situation in which binding of a ligand to a macromolecule does not affect the affinities of other binding sites oin the same molecule.

Front 11

Define:

Oxygenation

Back 11

The binding of molecular oxygen, e.g. to a heme group

Front 12

Define:

P₅₀

Back 12

For a gaseous ligand, the ligand concentration, in units of pressure (e.g. torr), at which a binding protein such as hemoglobin is half-saturated with ligand.

Front 13

Define:

pO₂

Back 13

Partial oxygen pressure

The concentration of gaseous O₂ in units of pressure (e.g. torr)

Front 14

Define:

R State

Back 14

One of two conformations of an allosteric protein; the other is the T state. The R state is usually the catalytically more active state.

Front 15

Define:

Sarcomere

Back 15

The repeating unit of a myofibril, consisting of thin and thick filaments that slide past each other during muscle contraction.

Front 16

Define:

Saturation

Back 16

The state in which all of a macromolecule's ligand-binding sites are occupied by a ligand.

See also enzyme saturation and saturated fatty acid.

Front 17

Define:

Sigmoidal curve

Back 17

The S-shaped graphical representation of the cooperative binding of a ligand to a molecule.

Front 18

Define:

Sliding Filament Model

Back 18

A mechanism for muscle contraction in which interdigitated thin and thick filaments move past each other so as to shorten the overall length of a sarcomere.

Front 19

Define:

Striated Muscle

Back 19

The voluntary or skeletal muscles, which have a striped microscopic appearance.

Front 20

Define:

T State

Back 20

One of two conformations of an allosteric protein; the other is the R state. The T state is usually the catalytically less active state.

Front 21

Define:

Thick filament

Back 21

The sarcomere element that is composed primarily of several hundred myosin molecules

Front 22

Define:

Thin filament

Back 22

The sarcomere element that is composed primarily of actin, along with tropomyosin and troponin.

Front 23

Define:

Yo₂

Back 23

Fractional Saturation (Y)
The fraction of a protein's ligand-binding sites that are occupied by ligand.

For example, Yo₂ is the fractional saturation of a protein's oxygen-binding sites.