Importance of Protein Analysis & the Assay Methods

Protein analysis is very important for

  1. Quantification of tissue or cell material in biological research.
  2. Understand body physiology
  3. For diagnosis of diseases by western blot, ELISA.
  4. To determine the mechanism of disease
  5. Quality control of packed food material and protein supplements.
  6. To develop vaccines.
  7. Biosynthesis of Hormones and Enzymes
  8. Forensic Investigation
  9. Identification of bacteria.

Protein is the widely distributed biomolecule in the body.

These proteins exist in different forms like the amino-acids, peptides, polypeptides, enzymes, hormones, etc. They carry out various functions in the body and almost all the body reactions occur with the involvement of protein.

Protein structure can be a single chain molecule, a 3-dimensional structure or even in a bundle or complex forms.

  1. Quantification of tissue or cell material:

In biological research, many a time cell contents, tissues are analyzed to study their physiology, morphology or other changes. This analysis is finally quantified in terms of per gram of protein or per microgram of protein.

This analysis of protein from the tissue sample is done by using the folin reagent method of Lowry.

Previously, the measurements were expressed in terms of a gram of tissue or biological sample.

  1. For diagnosis of diseases

Proteins are the major biochemicals which are widely used for diagnosis of diseases. They can be estimated from tissue and blood samples of a diseased patient. For example, diseases like HIV, hepatitis and more can be estimated by ELISA and western blot techniques.

Besides in anemia, hemoglobin analysis in the blood is done. The normal range for an adult woman is 12 to 16 gm/dL and in anemia, the level goes down drastically.

  1. To Understand body physiology:

Since proteins are present everywhere in the body, their analysis helps to understand the body function.

For example, hemoglobin is a protein present in the red blood cell and has iron it.hemoglobin protein

This iron helps to bind oxygen molecules. The change in the structural configuration of this protein along with iron the reason for gaseous exchange.

Similarly, digestion of proteins in the digestive tract is by the breakdown of proteins into peptides and then into amino acids.

  1. To determine the mechanism of disease

Many diseases have changes in protein physiology or nature. By analyzing proteins in the tissue, the disease mechanism can be understood. This helps to tackle the disease better with targeted drugs.

For example, in Alzheimer disease beta-amyloid protein plaques are formed. These proteins are toxic and disrupt nerve function.

  1. Quality control of packed food material and protein supplements.

Analysis of protein content is mandatory for the packed food industry. You can notice the label of packed foods to have to content of protein, carbohydrates and fats. This is necessary to inform the consumer about what the packet contains. Similarly, in protein supplements, the content of protein is indicated on the box. One with more than 99% of protein is sought by many.

  1. To develop vaccines

Vaccines are the immune-modifying substance which is used to develop resistance to disease. These vaccines contain a protein structure called epitome which can trigger an immune response in the host body. This leads to the formation of antibodies against that protein and can act as a defense for future exposure to that antigen from pathogens.

  1. Biosynthesis of Hormones and Enzymes

Diseases like diabetes, anemia require hormones like Insulin and erythropoietin for treatment. Previously, insulin was obtained from animals. A clear study of the molecular structure reveals that there is a difference in the amino acid of human and bovine insulin. So, the exact human hormones are prepared by rDNA technology using fermentation.

During preparation, chains of peptides are synthesized and then brought into a structural confirmation as the original hormones.

This synthesis of protein can be done due to the analysis of the protein structure before the actual method is designed for the entire process.

  1. Forensic Investigation

When there is a crime scene, most of the clues are collected including the hair, blood, other body tissue and fluid samples. These samples have protein in them and are analyzed to investigate the crime.

  1. Identification of bacteria

Bacterial identification is mostly done by cultures. But, this is a tedious and time-consuming process. Protein analysis using mass spectrometry is a faster and easy process.

Protein analysis & quantification

Protein being a biological entity is analyzed to determine the quantity, quality of protein and thereby the state of biological reaction or process.

They can be analyzed by methods like

  1. Folin reagent by lowry.
  2. Chemical methods of identification.
  3. Spectroscopic methods.

and the approach is different based on the need like

  • Protein sequence analysis
  • Protein structure analysis
  • Protein binding analysis
  • Crude protein analysis (quantification of protein).

Protein sequence analysis is necessary to analyze the sequence of amino acids or peptides in proteins like Insulin. Insulin was previously used from animals like pigs, cattle for diabetes treatment. But these insulin’s had side-effects due to the difference in the amino acids in the protein sequence. Hence biotechnology came up to solve the problem by providing an Insulin which has an exact sequence to human insulin with no side effects.

Protein structure analysis: proteins have different structures like secondary, tertiary, Quaternary, 3 fold structure, etc. These structures influence the function of protein for example 3 dimensional ones can carry some substances by either binding them over the surface or by encasing inside their structure etc. Chain and simple structure protein easily pass through cell walls.

This can be done by mass spectrometry, NMR spectroscopy, and X-Ray crystallography.

Crude protein analysis

This is done in terms of qualitative terms i.e to know the nature and type of protein.

Qualitative test for protein indicates the type of protein and is done by chemical methods.

Then it is also done in quantitative terms whereby the amount of protein in a given biological sample is known.

But for quantification of protein, the Lowry method as mentioned before is widely followed. This is a colorimetric procedure wherein the protein sample is treated to produce a dense color as a function of a protein. This color intensity is then estimated by using spectrophotometry for determination of the quantity of protein.

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