Question

what are the 4 levels of protein structure and what type of bonding leads to the formation of each of these types of protein structure?

Answer 1

ANSWER :-There are 4 types of protiens.So lets know what is protien first and then moving onto its classification.

Protiens ( called as building blocks of life) are highly complex molecules or macronutrients which play important role in our body. Protein molecules are  very large compared with molecules of sugar or salt and consists of many amino acids joined together to form long chains

There are three macronutrients: protein, fats and carbohydrates. Macronutrients provide calories, or energy. The body requires large amounts of macronutrients to sustain life. Chemically, protein is composed of amino acids, which are organic compounds made of carbon, hydrogen, nitrogen, oxygen or sulfur. Amino acids are the building blocks of proteins

Protein structure depends on its amino acid sequence which plays a major role in its function.There are 4 structures of protien.

1.PRIMARY STRUCTURE 2.SECONDARY STRUCTURE

3.TERTIARY STRUCTURE   4.QUATERNARY STRUCTURE

PRIMARY STRUCTURE

Primary Structure describes the structure in which amino acids are linked together to form a protein. Proteins are constructed from a set of 20 amino acids. PROPERTIES OF AMINO ACIDS ARE :

• A carbon (the alpha carbon) bonded to the four groups below:
• A hydrogen atom (H)
• A Carboxyl group (-COOH)
• An Amino group (-NH2)
• A "variable" group or "R" group

All amino acids have the alpha carbon bonded to a hydrogen atom, carboxyl group, and an amino group. The "R" group varies among amino acids and determines the differences between these protein monomers. The amino acid sequence of a protein is determined by the information found in the cellular genetic code. The order of amino acids in a polypeptide chain is unique and specific to a particular protein. Altering a single amino acid causes a gene mutation, which most often results in a non-functioning protein.

Amino acids are joined by peptide bonds. A peptide bond is a type of covalent bond

SECONDARY STRUCTURE

Stretches or strands of proteins or peptides have distinct, characteristic local structural conformations, or secondary structure, dependent on hydrogen bonding. There are two main types of secondary structure :- alpha helix and beta sheet.

α-Helix is a key secondary structure of natural proteins that consists of a peptide chain coiled into a right-handed spiral conformation and stabilized by hydrogen bonds between the NH and the CO groups in the backbone. Methionine, alanine, leucine, glutamate, and lysine have special propensity to be part of α-helix structures.

. The side-chain substituents of the amino acid groups in an α-helix extend to the outside. Hydrogen bonds form between the oxygen of each C=O bond in the strand and the hydrogen of each N-H group four amino acids below it in the helix. The hydrogen bonds make this structure especially stable. The side-chain substituents of the amino acids fit in beside the N-H groups.

In a beta-sheet two or more polypeptide chains run alongside each other and are linked in a regular manner by hydrogen bonds between the main chain C=O and N-H groups. Therefore all hydrogen bonds in a beta-sheet are between different segments of polypeptide which contrasts with the alpha-helix where all hydrogen bonds involve the same element of secondary structure. The R-groups (side chains) of neighbouring residues in a beta-strand point in opposite directions.

. The anti-parallel ß-sheet is more stable due to the more well-aligned hydrogen bonds.

Secondary structure is formally defined by the pattern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide

TERTIARY STRUCTURE

The tertiary structure of a protein refers to the arrangement of amino acid side chains in the protein. Generally, the information for protein structure is contained within the amino acid sequence of the protein itself.

The overall three-dimensional shape of a protein molecule is the tertiary structure. Although the three-dimensional shape of a protein may seem irregular and random, it is fashioned by many stabilizing forces due to bonding interactions between the side-chain groups of the amino acids.

There are four types of bonding interactions between "side chains" including: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions.

QUATERNARY STRUCTURE

quaternary structure is the arrangement of more than one protein molecule in a multi-subunit complex.Quaternary structure exists in proteins consisting of two or more identical or different polypeptide chains ( subunits ). These proteins are called oligomers because they have two or more subunits. The quaternary structure describes the manner in which subunits are arranged in the native protein. Subunits are held together by noncovalent forces; as a result, oligomeric proteins can undergo rapid conformational changes that affect biological activity.

The subunits are held together by hydrogen bonds and van der Waals forces