Proteins Macromolecules

Proteins are macromolecules with 4 different levels of structure. Amino acids in proteins range in structure with variations on their facet chains. The chemical composition of proteins and physical characteristics are established on the arrangement of the side chains. A predominant structure is made up of an amino acid sequence of the protein. Strands of proteins have distinct attribute formed as a result of secondary constructions which depend on hydrogen bonding. Each protein strand has a hydrogen bond that forms between a carbon and an oxygen atom. Tertiary shape is a 3-D shape of a protein molecule. Protein with tertiary shape achieves maximum stability after bending or twisting. The stabilized structure of tertiary protein allows for various amino acids to attach themselves therefore forming a protein structure that is held together by strong covalent bonds.
Proteins are the leading cause of no neurological diseases due to protein misfolding. Genes and proteins contribute diseases called amyloidogenic. The diseases include inherited cataracts, hemodialysis related disorders and type-2 diabetes. The diseases are as a result of a protein expression outside its normal context. The diseases are characterized by abnormality of proteins where some proteins experience misfolding during their formation. Misfolding results from genetic mutations that in stabilize the proteins hence the abnormalities. Protein imbalances can further be accelerated by deficiencies in proteasome.

Key words: Proteins, Amino Acids, Hydrogen Bonds, Misfolding
 
Protein

Introduction

Proteins are a vital part of the body which are used to perform many functions in the body. The main building blocks of proteins are the amino acids. Amino acids are classified as either essential or as non-essential. Our bodies require essential amino acids and are mainly found in the food. This type of amino acids cannot be made in the body and one depends on other sources for essential amino acids. On the other hand, non-essential amino acids are synthesized in the body and are not acquired from food. During the different periods of growth (infancy, childhood, adolescence and grown up) amino acids build up new body tissues which are used for growth and repair of worn out tissues. These amino acids are also used to synthesize enzymes, plasma proteins, antibodies (immunoglobulin) and some hormones which are used to regulate thousands of biochemical reactions in the cells and the body as a whole. When protein is consumed in excess of the body needs some is deaminated and excreted by the kidneys while some is converted to fat for storage in the fat deposits.
Proteins consist of three dimensional structures of amino acids, all arranged to form a protein molecule. The arrangements are classified as either primary, secondary, tertiary or quaternary structure. The simplest level is the primary structure which describes a series of amino acids arranged in a polypeptide chain. The polypeptide is held by strong bonds referred to as peptide bonds. On the other hand, a secondary structure describes several primary structures. In addition, the structure has hydrogen bonds classified as either alpha helix or beta sheet. An alpha helix represents a right handed coiled strand while the beta sheet happens to be between strands (Haggerty 2011, 46). Tertiary structure is composed of more than one secondary structures which represents the three dimensional shape of a protein molecule. Tertiary structure achieves the lowest energy state after bending and twisting of the protein molecule. Quaternary structure is also a three dimensional structure formed by aggregation of two or more individual polypeptide chains that function as single unit. Plants use nitrogen to make proteins but they cannot use nitrogen from the atmosphere. Therefore, they rely on microorganisms to fix the nitrogen to nitrate. These bacteria reside near the roots in specialized structures called root nodules where they have a symbiotic relationship with the plants. These nitrates are then taken in through the roots where they are converted to the 20 different kinds of amino acids. These special structures are called ribosomes. The already formed proteins are then sent to the Golgi apparatus where they are sent to different parts of the plant to form new structures and for metabolic processes.
Single cell protein (SCP) is an edible unicellular microorganism. The protein extract from the algae, yeast, fungi or bacteria may be used as an ingredient or a substrate for protein rich foods. This is attributed to the fact that it is amenable to controlled intensive cultivation and is less dependent on variation in climate and soil. They form their protein through protein catabolism into individual amino acids which are used to form bacterial proteins or oxidized to form energy. These microorganisms are found in many parts of our bodies and our environments for instance in enzymes.
An error in protein conformation leads to diseases. Proteins that have a complicated stability find it difficult to achieve a native stability. Therefore, an abnormal conformational transition to beta from alpha helix promotes protein aggregation by exposing the hydrophobic amino acid. (Perbal 2013, P.78). Under normal circumstances, the cell has the ability to prevent incorrect folding of a protein. When incorrect folding occurs, diseases such as Parkinson’s disease and amyotrophic lateral sclerosis occurs. Other diseases include Alzheimer’s disease, mad cow disease and the transthyretin amyloidosis. An effective therapy of protein related disease involves blocking of misfolded proteins from spreading and prevention of formation of pathological misfolded protein assemblies.

References

Haggerty, L. (2011). Protein structure. Hauppauge, N.Y.: Nova Science Publisher's.
Perbal, B. (2013). CCN proteins in health and disease. Dordrecht: Springer, pp.77-98.