Glossary

Author: Glossary

  • Phase I metabolism reactions

    The first phase of metabolism of foreign compounds (xenobiotics), involving metabolic activation. These reactions occur mainly in the liver but also in the small intestine and lungs and comprise the microsomal or mixed function oxidase system, NADPH- dependent enzymes and cytochrome P450 proteins. Generally regarded as detoxication reactions, but may in fact convert inactive precursors…

  • Pharmafoods

    Alternative name for functional foods.  

  • Phagophobia

    Phagophobia

    Fear of food; also known as sitophobia.    

  • Phagomania

    Morbid obsession with food; also known as sitomania.  

  • Potential hydrogen

    A measure of acidity or alkalinity. Defined as the negative logarithm of the hydrogen-ion concentration. The scale runs from 0, which is very strongly acid, to 14, which is very strongly alkaline. Pure water is pH 7, which is neutral; below 7 is acid, above is alkaline. The abbreviation used for potential hydrogen. pH represents…

  • Pescetarian

    Vegetarian who will eat fish, but not meat.  

  • Peptide linkage

    CONH linkage formed by reaction of an amine group of one amino acid with the carboxylic acid group of a second amino acid.  

  • Peptidases

    Enzymes that hydrolyse proteins, and therefore important in protein digestion. An enzyme that hydrolyzes (cleaves) a peptide bond. An enzyme which breaks down proteins in the intestine into amino acids. Digestive enzyme secreted by the small intestine that converts peptides to amino acids. One of a group of digestive enzymes that split proteins in the…

  • Pepsin

    An enzyme in the gastric juice which hydrolyses proteins to give smaller polypeptides; an endopeptidase. An enzyme found in gastric juice that promotes the digestion of proteins. A crystallizable proteinase (enzyme) that in an acidic medium digests (breaks down) most proteins to polypeptides. It is secreted by glands in the mucous membrane of the stomach…

  • Pentosuria

    The excretion of pentose sugars in the urine. Idiopathic pentosuria is an inherited metabolic disorder almost wholly restricted to Ashkenazi (North European) Jews, which has no adverse effects. Consumption of fruits rich in pentoses (e.g. pears) can also lead to (temporary) pentosuria. A condition in which pentose is present in the urine. A rare genetic…