at preventing/inhibiting tumors. However, if the cell’s DNA cannot be repaired, the p53 protein can then cause apoptosis (“programmed cell death”) to prevent development of (cancerous) tumors. See also GENE,

p53 GENE, TUMOR-SUPPRESSOR GENES, ras GENE, ras PROTEIN, GENETIC CODE, MEIOSIS, CARCINOGEN, DEOXYRIBONUCLEIC ACID (DNA), AFLATOXIN, RIBOSOMES, ONCOGENES, CANCER,

TUMOR, PROTO-ONCOGENES, PROTEIN, TRANSCRIP-

TION FACTORS, DOMAIN (OF A PROTEIN), APOPTO-

SIS.

Paclitaxel An anticancer compound (pharmaceutical) that was originally isolated from the Pacific yew tree (Taxus brevifolia), although it is made synthetically today. In 1966, Maurice Wall first identified antitumor effects in an extract from Taxus brevifolia. In 1992, the U.S. Food and Drug Administration approved paclitaxel for use to treat recurrent ovarian cancer. Other anticancer uses were later approved. When injected into the human body, paclitaxel also inhibits growth of the parasitic microorganism Toxoplasma gondii (which can cause loss of sight and neurological disease in humans, if not controlled). See also CANCER,

TAXOL™, FOOD AND DRUG ADMINISTRATION

(FDA), CHEMOTHERAPY, TUBULIN, MICROORGAN-

PPAF Acronym for Platelet Activating Factor.ISM, GROWTH (MICROBIAL).

See also CHOLINE.

PAGE See POLYACRYLAMIDE GEL ELECTROPHORE-

SIS (PAGE).

Palindrome A DNA molecule sequence that is the same when one strand of the molecule is read left to right and the other strand is read right to left. See also DEOXYRIBONUCLEIC

ACID (DNA), READING FRAME.

Palmitate See PALMITIC ACID.

Palmitic Acid A saturated fatty acid containing sixteen carbon atoms in its molecular “backbone”; which tends to increase cholesterol levels in the bloodstream when consumed by humans. It has been shown that feeding of extruded (whole) high-oleic oil soybeans to dairy cattle did decrease the content of palmitic acid in their milk. See also

FATTY ACID, SATURATED FATTY ACIDS (SAFA),

CHOLESTEROL, HIGH-OLEIC OIL SOYBEANS.

Pancreas An organ (gland) located near the stomach that secretes insulin and glucagon into the bloodstream, and digestive fluids into the intestines. See also DNASE, INSULIN,

GLUCAGON, BETA CELLS, TYPE I DIABETES, TYPE II

DIABETES, DIABETES.

Papovavirus A class of animal viruses, e.g., SV40 and polyoma. See also VIRUS.

Parkinson’s Disease A disease of the human brain, in which those nerve cells (neurons) associated with emotions and those neurons that are involved in controlling movement (motor control) die. Discovered in 1919 by doctors treating an epidemic of encephalitis lethargica (onset of Parkinson’s disease commonly follows encephalitis, but it can also be induced by certain drugs, etc.). The (natural) cause of Parkinson’s disease (i.e., causing a dwindling supply of dopamine in the brain) is unknown although it can be induced by drug misuse. When a human brain is functioning normally, cells within a region of the brain called the substantia nigra initiate motor (i.e., muscle) activity by releasing the chemical “messenger” known as dopamine. In the brain of a person suffering from Parkinson’s disease, those dopam- ine-producing cells die off, causing a progressive loss of motor control for that

person. See also NEUROTRANSMITTER, CILIARY NEUROTROPHIC FACTOR (CNTF), SIGNALING,

GLIAL DERIVED NEUROTROPHIC FACTOR (GDNF),

OXIDATIVE STRESS, NEURON.

PARP Acronym for Poly ADP-ribose Polymerase (an enzyme naturally present in human cells that is involved in control of apoptosis, among other cellular processes). This enzyme can be commercially produced (e.g., to manufacture tests) by genetically engineered hamster cells grown in cell culture. This enzyme can be utilized by man in order to determine/test if a given substance (e.g., industrial chemical) is carcinogenic to

humans. See also ENZYME, ADENOSINE DIPHOSPHATE (ADP), RIBOSE, POLYMERASE, CELL, APOPTOSIS, CELL CULTURE, MAMMALIAN CELL CULTURE, CARCINOGEN, CANCER, NUCLEAR MATRIX PROTEINS, GENETIC ENGINEERING, AMES TEST.

Particle Cannon See BIOLISTIC R GENE GUN,

MICROPARTICLES.

PLANT’S NOVEL TRAIT (PNT), PLANT VARIETY

PROTECTION ACT (PVP), EUROPEAN PATENT CON-

VENTION, EUROPEAN PATENT OFFICE (EPO), U.S.

PATENT AND TRADEMARK OFFICE (USPTO).

pBR322 An Escherichia coli (E. coli) plasmid cloning vector that contains the ampicillin resistance and tetracycline resistance genes. It consists of a circle of double-stranded

DNA. See also E S C H E R I C H I A C O L I F O R M

(E. COLI), PLASMID, VECTOR, DEOXYRIBONUCLEIC

ACID (DNA).

PC Phosphatidyl choline. See also LECITHIN

(refined, specific), LECITHIN (crude, mixture).

PCR See POLYMERASE CHAIN REACTION (PCR).

PDCAAS See PROTEIN DIGESTIBILITY-CORRECTED

AMINO ACID SCORING (PDCAAS).

PDE See PHOSPHODIESTERASES.

PDGF See PLATELET-DERIVED GROWTH FACTOR

(PDGF).

PDWGF See PLATELET-DERIVED WOUND GROWTH

FACTOR (PDWGF).

Pectinophora gossypiella Also known as the pink bollworm, this is one of three insect species that are called “bollworms” (when they are on cotton plants). The holes that they chew in cotton plants’ bolls have been shown to enable the Aspergillas flavus fungus to infect those (chewed) cotton plants.

See also B.t. KURSTAKI, HELICOVERPA ZEA (H. ZEA),

HELIOTHIS VIRESCENS, BRIGHT GREENISH-YELLOW

PFLUORESCENCE (BGYF).

PEG-SOD (polyethylene glycol superoxide dismutase) A modified version of the enzyme human superoxide dismutase (hSOD), in which polyethylene glycol (a polymer made up of ethylene glycol monomers) is combined with the hSOD molecule. The PEG seems to wrap around or about the enzyme in such a way that the whole complex is able to exist in the blood for longer periods of time than the unmodified hSOD enzyme. This is because the PEG effectively camouflages the hSOD molecule and hence protects it from being inactivated by the body’s own defense mechanisms in the bloodstream. This technology is important in that hSOD is used to fight certain diseases by injecting it into the body. However, the SOD must be present in the body for extended periods of time in order to effectively work, and since the injected SOD is a

foreign molecule, the body tries to destroy it (and hence its function) as quickly as pos-

sible. See also HUMAN SUPEROXIDE DISMUTASE

(hSOD), CATALASE, ENZYME.

Penicillin G (benzylpenicillin) The original penicillin (antibiotic) molecule, discovered by Alexander Fleming in 1928, in a petri dish (experiment) ‘spoiled’ by accidental introduction of a mold. Fleming named the antibiotic after the particular mold (Penicillium notatum) that had produced it. During the 1940s, scientists at the U.S. Department of Agriculture in Peoria, Illinois (in the U.S.), discovered how to produce commercial quantities of Penicillin G by utilizing the fungus Penicillium chrysogenum, which they found growing on a canteloupe in Peoria. Penicillin kills bacteria by blocking an enzyme which is crucial to growth and repair of the bacteria’s cell wall (peptidoglycan layer), but penicillin does not harm other species, so it is species-specific to certain pathogenic bacteria (e.g., streptococcus, meningococcus, and diphtheria bacillus).

See also ANTIBIOTIC, FUNGUS, BACTERIA,

ENZYME, SPECIES SPECIFIC, PENICILLIUM, BETA-

LACTAM ANTIBIOTICS, BACILLUS.

Penicillinases (E.C. 3.5.2.6) Also known as

β-lactamases, these are enzymes that hydrolyze (break down) the β-lactam ring (portion) of the penicillin molecule’s structure. Some microorganisms (e.g., pathogenic bacteria) have become able to produce these enzymes as a defense to penicillin and cephalosporin antibiotics (drugs). See also

ENZYME, HYDROLYZE, PENICILLIN G (BENZYLPEN-

ICILLIN), PATHOGENIC, BACTERIA, ANTIBIOTIC,

ANTIBIOTIC RESISTANCE.

Penicillium Refers to the genus of fungi (mold) that belongs to the category Deutromycotina and often causes (food) spoilage. Some of the genus have been utilized commercially to produce antiboiotics. See also

GENUS, FUNGUS, OCHRATOXINS, ANTIBIOTIC, PEN-

ICILLIN G (benzylpenicillin).

Pentose A simple sugar (monosaccharide molecule) whose backbone structure contains five carbon atoms. There exists many different pentoses. Some examples of pentoses are ribose, arabinose, and xylose. See also

MONOSACCHARIDES.

Pepsin 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 of higher animals. In combination with dilute hydrochloric acid, it is the chief active principle (component) of gastric juice. Also used in manufacturing peptones and in digesting gelatin for the recovery (i.e., recycling) of silver from photographic film.

See also DIGESTION (WITHIN ORGANISMS), PROTEIN, PEPTIDE, LACTOFERRIN, PEPTONE.

Peptidase A n e n z y m e t h a t h y d r o l y z e s (cleaves) a peptide bond. See also PEPTIDE

BOND, PEPSIN, PEPTONE, PEPTIDE MAPPING

(“FINGERPRINTING”).

Peptide Two or more amino acids covalently joined by peptide bonds. An oligomer component of a polypeptide. A dipeptide, for example, consists of two (di) amino acids joined together by a peptide bond or linkage. By analogy, this structure would correspond to two joined links of a chain. See also

POLYPEPTIDE (PROTEIN), OLIGOMER, AMINO ACID.

Peptide Bond A covalent bond (linkage) between the α-amino group of one amino acid and the α-carboxyl group of another amino acid. This is the linkage or bond which holds the amino acids (chain links) together in a polypeptide chain. It is the allimportant bond which holds the amino acid monomers together to form the polymer known as a polypeptide. See also PEPTIDE,

POLYPEPTIDE (PROTEIN), OLIGOMER.

Peptide Mapping (fingerprinting) Refers to the characteristic pattern of peptides (i.e., pieces that make up a protein molecule) resulting from partial hydrolysis (cleavage, digestion) of a protein. The pattern (fingerprint) is obtained by separating the peptides via two-dimensional chromatography, in which the peptides are first subjected to chromatography using one solution which separates many, but not all, peptides. The chromatogram is then turned 90°, and is again chromatographed using a second solution, which then separates all of the peptides; thereby producing the final “fingerprint” of the protein. See also CHROMATOGRAPHY,

PEPTIDE, PROTEIN, HYDROLYSIS.

Peptide Nanotube See SELF-ASSEMBLY (OF A

LARGE MOLECULAR STRUCTURE).

Peptido-Mimetic See BIOMIMETIC MATERIALS,

PEPTIDE.