PEC Polyethylene glycol; a polymer that usually consists of a size distribution of various molecular weight compounds. Physical and chemical properties vary with the molecular weight (liquid to solid, viscosity, etc.). PEGs are used as surfactants in industry (for foods, cosmetics, and pharmaceuticals); and in biomedicine as dispersing agents, solvents, ointment and suppository bases, vehicles, and excipients.

PEGylation Covalent attachment of polyethylene glycol molecule(s) to a protein molecule via selected amino acid side groups, for example free amino or sulfhydryl groups. May be done to decrease toxicity or improve its solubility and circulating half-life in the body.

Visualization of a complex population of PEG structures by HDMS.

peptides Short polymers formed from the linking, in a defined order, of amino acids. The link between one amino acid residue and the next is known as an amide bond or a peptide bond.

perfusion Sometimes perfusion propagation; a cell culture or fermentation process commonly used in antibody production, in which high concentrations of mammalian cells inside a chamber have fresh growth media continually circulated around them for continuous addition of nutrients and removal of waste products.

permeate Also called filtrate, the part of a mixture that passes through a filter.

pH Power of hydrogen or the log of the concentration of H+ ion in a solution. Measurement of the relative alkalinity or acidity of a solution. Pure water is pH neutral (7), acidic solutions have pH values between 0 and 7, and alkaline or basic solutions have pH values between 7 and 14. Often a critical control parameter in biopharmaceutical processes.

phage A virus-like parasite that infects bacteria; also bacteriophage.

pharmaceutical development Collected information from development studies conducted to establish that the dosage form, formulation, manufacturing process, and quality attributes are appropriate for the product. The development process should identify and describe the critical quality attributes and critical process parameters that influence product quality and performance.

pharmacodynamics Study of the reactions between drugs and living structures, including the processes of bodily responses to pharmacological, biochemical, physiological, and therapeutic effects. A PD study seeks to determine where a drug penetrates in the body and by means of what mechanisms.

pharmacokinetics Study of the ADME processes for compounds and medicines. (See also ADME)

Phe Phenylalanine; one of more than 20 naturally occurring amino acids.

phenotype The observable characteristic that results from the action of an organism's genes. Phenotype varies depending on which alleles of each gene are present.

phosphoramidite or nucleoside phosphoramidites The individual base building blocks that are used to synthesize short nucleic acid chains also known as oligo-nucleotides.

phosphorylation Addition of a phosphate (PO4) group to a molecule, usually enzymatically done by transferring a phosphate group from ATP (adenosine triphosphate).

physical state The form that matter takes, whether solid, liquid, gas, or plasma.

Peptide mapping provides detailed structural information for a protein; it is a challenging application because of the number of peaks that must be baseline-resolved. The Waters UPLC Peptide Analysis Solution, with Peptide Separation Technology Columns, provides maximum resolution and sensitivity for more confidence in protein characterization studies.