proteins

What is the relationship between amino acid sequence and the diversity in form and function of proteins? How are protein molecules affected by their chemical and physical environments?

reactants and products of a condensation reaction

reactants: amine group of 7 amino acids and the carboxyl group of another

products: H2O and peptide bond

essential amino acid

amino acids cannot be synthesized naturally and must be obtained from food.

nonessential amino acid

amino acids can be made from other amino acids.

equation for the number of possible amino acid sequences

20^n

what causes a proteins shape

This shape is the result of interactions between the R-groups of the protein

when a solution becomes too acidic:

the excess H⁺ ions will interact with the “- “ charges of R-groups

when a solution becomes too basic:

the excess OH^- ions will interact with the “+” charges of R-groups

what happens if you change the charges of the R groups

Changing the charges of these the R-groups disrupt the ionic bonds that give proteins give their 3D structure

the only exception to the pH level of solutions affecting proteins:

Pepsin, it works at the pH of 1.5 found in the stomach

temperature effect on protein structure

As temperature increases, kinetic energy increases and causing the bonds that hold the protein together to vibrate and eventually break

exception to temperature’s effect on protein structure

Taq polymerase used for Polymerase Chain Reaction (PCR) works best at 72°C

zwitterions meaning

Amino acids are zwitterions (they contain both, negatively COO^- a positively NH3⁺ charged regions at neutral pH)

how does a change in pH affect protein structures

A change in pH will alter the charge of the protein by changing the COOH and NH2 groups

what gives amino acids their character

The amine groups and the carboxyl groups are used in forming the polypeptide chain, so it is the R groups that give amino acids their individual character

primary structure

basic amino acid chain

secondary structure

Created by the formation of H-bonds between the COOH group of one amino acid and the NH group of another.

-a-helix

-β-pleated sheet

tertiary structure

The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups

disulfide bonds

(bridges) between S of cystines which form covalent bonds

H bonds

between R polar groups with OH or NH

hydrophobic (Vander Waals)

between non-polar R groups

ionic bonds

between + and - R groups

hydrophillic amino acids role in protein channels

polar hydrophilic amino acids line the protein channels and hydrophobic amino acids hold them in a transmembrane position. allows hydrophillic molecules like water or ions to easily pass through channel.

globular proteins

have hydrophillic amino acids on their surface and a hydrophpbic core to stabilize. need to be in contact with water

quaternary structure

involves multiple polypeptide chains, which combine to form a single structure. may include a prosthetic or non-polypeptide group

conjugated proteins

Conjugated proteins, also known as compound proteins, are proteins that contain a non-protein component in addition to amino acids. This non-protein component, called a prosthetic group, can be a lipid, carbohydrate, or a metal ion. The prosthetic group is covalently attached to the protein and plays a crucial role in the protein's structure and function.

hemoglobin

a conjugated protein, contains a non-polypeptide group called Heme (Iron)

fibrous proteins shape and structure

no folding into tertiary structure, elongated polypeptide, often no alha helixes, narrow fibers or filaments

fibrous proteins solubility in water

insoluable

fibrous proteins function

structural support, high tensile strength, skin, tendons, ligaments, cartilage

fibrous protein examples

spider silk, collagen, keratin, elastin

globular protein shape and structure

rounded shape, many interactions between R groups in tertiary structure

globular protein solubility in water

soluable

globular proteins function

often involved in ligand binding, transport, membrane proteins, enzymes

globular proteins examples

hemoglobin, insulin, enzymes

the monomer of proteins

amino acid

proteins that are used in the human immune system

immunoglobins

denaturng a protein…

disrupts the 3D structure of the molecule