Proteins, Amino Acids, and Enzymes Study Set

Vocabulary practice flashcards covering protein structure, amino acid properties, biochemical separation methods, and enzyme kinetics based on the lecture transcript.

Amino kiseline

Molekuli niske molekulske težine koji sadrže najmanje dvije funkcionalne grupe: amino grupu i karboksilnu grupu.

L-konformacija

Specifičan prostorni raspored gde se amino grupa nalazi u L-poziciji u odnosu na karboksilnu grupu na $\beta$-ugljenikovom atomu, koja se nalazi u gotovo svim prirodnim proteinima.

L-konformacija

Specifičan prostorni raspored gde se amino grupa nalazi u L-poziciji u odnosu na karboksilnu grupu na $\beta$-ugljenikovom atomu, koja se nalazi u gotovo svim prirodnim proteinima.

Zwitterion (Cviterjon)

A dual-ion structure occurring at physiological pH where the amino group is protonated ($NH_3^+$) and the carboxyl group is dissociated ($COO^-$), resulting in a net neutral charge.

Isoelectric Point (IET / pl)

The specific pH value at which the total net charge of an amino acid or protein is equal to zero.

Ninhydrin Reaction

A characteristic reaction for all amino acids with a free amino group (except proline and hydroxyproline) that produces a blue or purple-colored unit.

Hydrophobic Interactions

Interactions occurring between amino acids with non-polar and non-ionized R-groups, such as Glycine, Alanine, Valine, Leucine, and Isoleucine.

Cysteine (Cys)

A polar amino acid containing a sulfhydryl group ($SH$) that can form covalent disulfide bonds ($S-S$).

Peptides

Compounds formed by joining up to $100$ amino acids via peptide bonds; chains exceeding $100$ amino acids are classified as proteins.

Peptide Bond

A covalent, rigid bond formed through a reaction between the carboxyl group of one amino acid and the amino group of another, releasing a water molecule.

Edman Degradation

A chemical reaction using phenylisothiocyanate to determine the amino acid sequence by identifying residues from the N-terminal end one by one.

Sanger's Reaction

A method using dansyl chloride to identify the N-terminal amino acid of a peptide, though it causes hydrolysis of all other peptide bonds.

Glutathione

A specific tripeptide (glutamic acid, cysteine, glycine) that acts as a biological antioxidant and participates in amino acid transport.

Skleroproteins

Water-insoluble proteins with fibrillar structures and structural functions, such as collagen and keratin.

Globular Proteins

Water-soluble proteins with a spherical shape, including blood plasma proteins, egg white, and all enzymes.

Proteids

Complex proteins consisting of a dominant protein part and an associated non-protein component, such as glycoproteins or lipoproteins.

Primary Structure of Proteins

The linear sequence of amino acids in a protein chain linked by peptide bonds, which determines the protein's overall function and higher-level structures.

Secondary Structure of Proteins

The spatial arrangement of the polypeptide chain, such as $\alpha$-helix or $\beta$-pleated sheets, stabilized by hydrogen bonds between peptide bond components.

Tertiary Structure (Native Conformation)

The final three-dimensional orientation of a polypeptide chain in space, determined by all interactions between amino acid side chains.

Quaternary Structure

The structural level found in proteins with multiple polypeptide chains that communicate via cooperativity.

Isoelectric Focusing

An electrophoresis technique that separates proteins based on their IET using a gel with a pH gradient.

Michaelis Constant ($K_M$)

The substrate concentration at which the reaction rate is half of the maximum velocity ($V_{max}/2$); it indicates the enzyme's affinity for the substrate.

Apoenzyme

The protein component of an enzyme that requires a non-protein part (coenzyme) for activity.

Holoenzyme

The complete, catalytically active enzyme formed by the combination of an apoenzyme and a coenzyme.

Induced Fit Model

A mechanism where the enzyme's active site undergoes a conformational change upon substrate approach to achieve a perfect binding fit.

Allosteric Enzymes

Enzymes with quaternary structure that exhibit a sigmoid activity curve and transition between Tense (T) and Relaxed (R) conformations.

Hill Coefficient ($h$)

An exponent used in the kinetic equation for allosteric enzymes to describe the degree of cooperativity between subunits.