Protein: From 3 Different Sources
Molecular constituent of all cells comprising amino acid building blocks.
The term applies to members of a group of non-crystallisable nitrogenous substances widely distributed in the animal and vegetable kingdoms, and forming the characteristic materials of their tissues and ?uids. They are essentially combinations of AMINO ACIDS. They mostly dissolve in water and are coagulated by heat and various chemical substances. Typical examples of protein substances are white of egg and gelatin.
Proteins constitute an essential part of the diet as a source of energy, and for the replacement of protein lost in the wear and tear of daily life. Their essential constituent from this point of view is the nitrogen which they contain. To be absorbed, or digested, proteins have to be broken down into their constituent amino acids. The adult human body can maintain nitrogenous equilibrium on a mixture of eight amino acids, which are therefore known as the essential (or indispensable) amino acids. They are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. In addition, infants require histidine.
n. one of a group of organic compounds of carbon, hydrogen, oxygen, and nitrogen (sulphur and phosphorus may also be present). The protein molecule is a complex structure made up of one or more chains of *amino acids, which are linked by peptide bonds. Proteins are essential constituents of the body; they form the structural material of muscles, tissues, organs, etc., and are equally important as regulators of function, as enzymes and hormones. Proteins are synthesized in the body from their constituent amino acids, which are obtained from the digestion of protein in the diet. Excess protein, not required by the body, can be converted into glucose and used as an energy source (*gluconeogenesis).
The presence of protein in the urine, sometimes a symptom of kidney compromise. See ALBUMINURIA... proteinuria
A protein produced in the body in response to inflammation.... c-reactive protein
A protein produced in the gut and liver of the FETUS. Abnormality in the fetus, such as neural tube defect, may result in raised levels of alphafeto protein in the maternal blood. In DOWN’S (DOWN) SYNDROME, levels may be abnormally low. In either case, screening of the pregnancy should be carried out, including AMNIOCENTESIS to check the amount of alpha-feto protein in the amniotic ?uid. The protein may also be produced in some abnormal tissues in the adult – in patients with liver cancer, for example.... alpha-feto protein
Reagent used by intradermal administration in the Mantoux (tuberculin) test for TB.... purified protein derivative (ppd)
Proteins present in blood plasma, including albumin, blood clotting proteins, and immunoglobulins.... plasma proteins
Large molecules consisting of hundreds or thousands of amino acids linked into long chains. Proteins may also contain sugars (glycoproteins) and lipids (lipoproteins). There are 2 main types of proteins. Fibrous proteins are insoluble and form the structural basis of many body tissues. Globular proteins are soluble and include all enzymes, many hormones, and some blood proteins, such as haemoglobin.... proteins
The formation of protein molecules through the joining of amino acids.... protein synthesis
a protein of low molecular weight found in the urine of patients with multiple *myeloma and rarely in patients with *lymphoma, *leukaemia, and *Hodgkin’s disease. [H. Bence-Jones (1814–73), British physician]... bence-jones protein
(PTH-RP) a protein that is secreted by certain malignant tumours and is the main cause of malignant *hypercalcaemia. PTH-RP, which has effects similar to *parathyroid hormone, stimulates generalized bone resorption and excessive calcium reabsorption in the kidney tubules. It is most commonly produced by lung tumours, squamous-cell carcinomas of other organs, melanomas, and tumours of the breast, liver, pancreas, bladder, and prostate.... parathyroid hormone-related protein
an enzyme that catalyses the transfer of a phosphate group from ATP to a specific amino acid residue of an intracellular protein (usually serine, threonine, or tyrosine), thereby affecting the biological activity of the protein. Protein kinase inhibitors are drugs that block the action of protein kinases in tumour cells and are used in the treatment of cancer. They include *sorafenib, *sunitinib, and *temsirolimus. See also tyrosine kinase inhibitor.... protein kinase
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