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
peptide bond The carbon-nitrogen covalent bond (link) between an amino group of one amino acid and a carboxyl group of another, formed
by removing water and resulting in the group RCO-NH. This linkage does not allow free rotation, and it is the important bond
that connects amino acid monomers to form the polymer known as a polypeptide.
Visualization of a complex population of PEG structures by HDMS.
peptide mapping Bioanalytical method in which proteins are selectively cleaved by enzymes to create a characteristic pattern of peptides that
is elucidated through chromatographic separations and spectroscopic or spectrometric detection.
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)
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
physical state The form that matter takes, whether solid, liquid, gas, or plasma.
Isoelertric point; the pH at which a substance has no net charge, above which a substance acts as a base and below which it acts as an acid.
A solution of proteins or amino acids has its minimum conductivity and viscosity at the isoelectric point. The pI is a pH
value for a given substance; for example, the pI of gelatin is pH 4.7. pI can be used to identify and characterize proteins..
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.