Unit-3-Chemistry-of-Proteins

Amino Acid

A compound containing both a carboxyl (-COOH) group and an amino (-NH2) group; the building blocks of proteins.

Zwitterion

A molecule with both positive and negative charges, making it overall neutral, found in standard amino acids at physiological pH.

Denaturation

A process that disrupts the three-dimensional structure of a protein, usually caused by factors such as heat or chemicals, leading to loss of function.

Isoelectric Point (pI)

The pH at which an amino acid exists primarily in its zwitterion form, resulting in no net charge.

Peptide Bond

A covalent bond formed between two amino acids through a condensation reaction, resulting in the release of water.

Essential Amino Acids

Amino acids that cannot be synthesized by the body and must be obtained from the diet; there are 10 essential amino acids.

Hydrophilic

A property of molecules that are water-soluble, often associated with polar or charged side chains of amino acids.

Hydrophobic

A property of molecules that are water-insoluble and tend to cluster together in proteins, typically associated with nonpolar side chains.

Primary Structure

The specific sequence of amino acids in a polypeptide chain, determining the protein's overall structure and function.

Quaternary Structure

The arrangement of multiple polypeptide chains (subunits) in a protein, only existing in multi-chain proteins.

Protein Hydrolysis

The process of breaking down proteins into their constituent amino acids by breaking peptide bonds, usually involving acids, bases, or enzymes.

Functional Group

A specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule.

Amphoteric

Substances that can act as both acids and bases; amino acids are considered amphoteric because they contain both carboxyl and amino groups.

Disulfide Bonds

Covalent bonds formed between cysteine residues in proteins, which help stabilize the protein's structure.

Hydrogen Bonds

Weak interactions that occur between a hydrogen atom and an electronegative atom, crucial for stabilizing secondary structures in proteins.

Polypeptide

A polymer of amino acids linked by peptide bonds; generally larger than short peptides but may refer to any chain of amino acids.

Peptide Nomenclature

The systematic naming of peptides, where the C-terminal amino acid retains its full name and the others take on the -yl suffix.

Hydrophobic Interaction

The tendency of nonpolar molecules to avoid water molecules and aggregate together, often critical for protein folding and stability.

Enantiomers

Stereoisomers that are non-superimposable mirror images of each other, often related to amino acids with chiral centers.

Myoglobin

A globular protein that binds oxygen in muscle tissues, functioning primarily in oxygen storage.

Hemoglobin

A tetrameric protein that carries oxygen in the blood and exhibits cooperative binding due to quaternary structure.

Chiral Center

A carbon atom attached to four different groups, making the molecule asymmetric; critical in identifying L and D forms of amino acids.

Secondary Structure

Local folding patterns within a protein, often in the form of alpha-helices or beta-pleated sheets, stabilized by hydrogen bonds.

Amide Bond

Another name for a peptide bond due to the bonding characteristics of peptide formation in proteins.

Peptide Chain Directionality

The orientation of a peptide chain from N-terminal (amino end) to C-terminal (carboxyl end), defining its sequence.

Amino Acid Structure

Organic molecules featuring a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a side chain (R group) that defines its unique properties.

Classification of Amino Acids

Amino acids are sorted based on the characteristics of their side chains into categories such as polar, nonpolar, acidic, and basic, which affects their functional roles within proteins.

Amphoteric Nature of Amino Acids

Amino acids possess amphoteric qualities, enabling them to function as either acids or bases due to their dual presence of amino and carboxyl groups.

Significance of Essential Amino Acids in Diet

Essential amino acids are crucial components that the body cannot produce and must be acquired from dietary sources, as they are vital for growth, repair, and metabolic processes.

Mechanism of Peptide Bond Formation

Peptide bonds are established through a condensation reaction, connecting the carboxyl group of one amino acid to the amino group of another while releasing a water molecule.

Peptide Naming Convention

Peptides are systematically named whereby the C-terminal amino acid retains its complete name, while preceding amino acids adopt the -yl suffix, which ensures precise identification.

Role of Glutathione in Biology

Composed of glutamate, cysteine, and glycine, glutathione functions as a significant antioxidant, aiding in the protection of cells from oxidative stress.

Primary Structure of Proteins

Refers to the specific linear sequence of amino acids in a polypeptide chain, which ultimately dictates the protein's structure and function.

Secondary Structure in Proteins

encompasses regions of localized folding, such as alpha helices and beta sheets, stabilized mainly by hydrogen bonding.

Tertiary Structure Explanation

the three-dimensional configuration of a protein, maintained by various interactions including disulfide bonds, hydrogen bonds, hydrophobic interactions, and metal ion coordination.

Quaternary Structure Definition

involves the spatial arrangement and interaction among multiple polypeptide strands within a protein, exemplified by hemoglobin, which is composed of several subunits working together to transport oxygen.