10-03-2012, 07:04 PM
(This post was last modified: 10-03-2012, 07:52 PM by Administrator.)
Proteins are called as the “building blocks of body” which has significant role in all cellular functions contributing to the overall function of the body. Proteins are the key structures in all biochemical and metabolic pathways of a human body. The dominance of proteins in cell functions is highly commendable, which lead to the development of various fields like proteomics and protein biotechnology enabling the complete understanding and study of proteins under one roof.
The basic units of the proteins are called as amino acids. One or more amino acids linked by peptide bond contribute to the structure of protein. The amino acid sequence is specific for each protein and the sequence of amino acids is controlled by gene sequence. There are twenty different amino acids and they are Glycine, Alanine, Leucine, Isoleucine, histidine, methionine, phenylalanine, cysteine, glutamine, glutamic acid, asparagines, aspartic acid, proline, serine, threonine, tryptophan, tyrosine, valine, arginine and lysine. The various combination of these amino acids result in a specific type of protein. Thus any alteration or absence of even a single amino acid in an amino acid sequence results in protein dysfunction.
Proteins are classified based on their structure, function and composition. Proteins are grouped under primary, secondary, tertiary and quaternary types based on their structure. The factors like solubility and shape classifies proteins as fibrous, globular and intermediate proteins. Some examples of fibrous proteins are elastin, collagen and keratin which are insoluble in water. Globulin and insulin are globular proteins, soluble in water. Intermediate proteins depict the nature of fibrous proteins in shape and solubility like globular proteins. Fibrinogen is a classic example of an intermediate protein.
Based on the protein composition, they are grouped into simple and conjugated proteins. The simple proteins are the ones which are made up of only amino acids whereas the conjugated proteins represent the presence of proteins along with other molecules. The albumins, globulins, histones and scleroproteins are simple proteins. The lipoproteins, glycoprotein, nucleoprotein, chromoprotein phosphoprotein, flavoprotein and metaloprotein are all conjugated proteins. Based on their function proteins are grouped under categories like enzyme, storage, transport, hormonal, receptor, contractile, defensive and genetic proteins.
Most of the proteins are synthesized in the human body by transcription of DNA into mRNA (messenger RNA) and translation of mRNA into amino acids (proteins) with the help of tRNA (transfer RNA). Some proteins are derived from the dietary supplements like meat, egg, milk, vegetables, pulses and nuts. The deficiency or dysfunction of the bodily synthesized protein and deficiency of dietary protein causes various diseases.
Since all the synthesis and sequence of amino acids are controlled by genes, any mutation in the gene causes either dysfunction of the protein or absence of the protein. As a result various diseases and syndromes develop. Marfan Syndrome (dysfunction of fibrillin protein due to mutation of FBN1 gene), Huntington disease (dysfunction of huntingtin protein resulting in excess glutamine), Hereditary hemochromatosis associated with the HFE protein, Alzheimer’s disease are some of the diseases identified as a result of protein dysfunction due to gene abnormality or mutation. Transmissable spongiform encephalopathies like mad cow disease, Creutzfeld Jakob disease (prion disease), cancer, cystic fibrosis are diseases due to misfolding of proteins or absence of correctly folded proteins. Phenylketonuria is a condition in children whose ability to degrade the amino acid phenylalanine is disturbed.
Kwashiorkor, Marasmus and Marasmic- Kwashiorkor (grouped under Protein-Energy malnutrition) diseases are the mainly discussed dietary protein deficiency related disorders. To combat these disorders, required quantity of protein intake through diet is suggested based on the severity of the disease. Also excess intake of protein poses problems like ketosis, kidney and liver related disorder and so on. The other diseases like hypertension, diabetes which imposes stress on kidney resulting in kidney failure is associated with a condition called proteinuria where the essential proteins passes through kidney and appears in urine.
The protein related disorders due to dietary intake is well managed. If the disease is due to malnutrition of protein, then the patient is given protein rich diet or if it is due to excess intake of protein then the patient is restricted of protein intake. Whereas the treatment of genetic related protein disorders or syndromes is quite challenging and the subject of gene therapy should be understood and considered for treatments.
The basic units of the proteins are called as amino acids. One or more amino acids linked by peptide bond contribute to the structure of protein. The amino acid sequence is specific for each protein and the sequence of amino acids is controlled by gene sequence. There are twenty different amino acids and they are Glycine, Alanine, Leucine, Isoleucine, histidine, methionine, phenylalanine, cysteine, glutamine, glutamic acid, asparagines, aspartic acid, proline, serine, threonine, tryptophan, tyrosine, valine, arginine and lysine. The various combination of these amino acids result in a specific type of protein. Thus any alteration or absence of even a single amino acid in an amino acid sequence results in protein dysfunction.
Proteins are classified based on their structure, function and composition. Proteins are grouped under primary, secondary, tertiary and quaternary types based on their structure. The factors like solubility and shape classifies proteins as fibrous, globular and intermediate proteins. Some examples of fibrous proteins are elastin, collagen and keratin which are insoluble in water. Globulin and insulin are globular proteins, soluble in water. Intermediate proteins depict the nature of fibrous proteins in shape and solubility like globular proteins. Fibrinogen is a classic example of an intermediate protein.
Based on the protein composition, they are grouped into simple and conjugated proteins. The simple proteins are the ones which are made up of only amino acids whereas the conjugated proteins represent the presence of proteins along with other molecules. The albumins, globulins, histones and scleroproteins are simple proteins. The lipoproteins, glycoprotein, nucleoprotein, chromoprotein phosphoprotein, flavoprotein and metaloprotein are all conjugated proteins. Based on their function proteins are grouped under categories like enzyme, storage, transport, hormonal, receptor, contractile, defensive and genetic proteins.
Most of the proteins are synthesized in the human body by transcription of DNA into mRNA (messenger RNA) and translation of mRNA into amino acids (proteins) with the help of tRNA (transfer RNA). Some proteins are derived from the dietary supplements like meat, egg, milk, vegetables, pulses and nuts. The deficiency or dysfunction of the bodily synthesized protein and deficiency of dietary protein causes various diseases.
Since all the synthesis and sequence of amino acids are controlled by genes, any mutation in the gene causes either dysfunction of the protein or absence of the protein. As a result various diseases and syndromes develop. Marfan Syndrome (dysfunction of fibrillin protein due to mutation of FBN1 gene), Huntington disease (dysfunction of huntingtin protein resulting in excess glutamine), Hereditary hemochromatosis associated with the HFE protein, Alzheimer’s disease are some of the diseases identified as a result of protein dysfunction due to gene abnormality or mutation. Transmissable spongiform encephalopathies like mad cow disease, Creutzfeld Jakob disease (prion disease), cancer, cystic fibrosis are diseases due to misfolding of proteins or absence of correctly folded proteins. Phenylketonuria is a condition in children whose ability to degrade the amino acid phenylalanine is disturbed.
Kwashiorkor, Marasmus and Marasmic- Kwashiorkor (grouped under Protein-Energy malnutrition) diseases are the mainly discussed dietary protein deficiency related disorders. To combat these disorders, required quantity of protein intake through diet is suggested based on the severity of the disease. Also excess intake of protein poses problems like ketosis, kidney and liver related disorder and so on. The other diseases like hypertension, diabetes which imposes stress on kidney resulting in kidney failure is associated with a condition called proteinuria where the essential proteins passes through kidney and appears in urine.
The protein related disorders due to dietary intake is well managed. If the disease is due to malnutrition of protein, then the patient is given protein rich diet or if it is due to excess intake of protein then the patient is restricted of protein intake. Whereas the treatment of genetic related protein disorders or syndromes is quite challenging and the subject of gene therapy should be understood and considered for treatments.
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