P
PAGE (polyacrylamide gel electrophoresis) A type of *electrophoresis used to determine the size and
composition of proteins. Proteins are
placed on a matrix of polyacrylamide
gel and an electric Üeld is applied.
The protein molecules migrate towards the positive pole, the smaller
molecules moving at a faster rate
through the pores of the gel. The proteins are then detected by applying a
stain.
PAH Polyaromatic hydrocarbon. See
particulate matter.
palladium Symbol Pd. A soft white
ductile *transition element (see also
platinum metals); a.n. 46; r.a.m.
106.4; r.d. 12.02; m.p. 1552°C; b.p.
3140±1°C. It occurs in some copper
and nickel ores and is used in jewellery and as a catalyst for hydrogenation reactions. Chemically, it
does not react with oxygen at normal
temperatures. It dissolves slowly in
hydrochloric acid. Palladium is capable of occluding 900 times its own
volume of hydrogen. It forms few
simple salts, most compounds being
complexes of palladium(II) with some
palladium(IV). It was discovered by
William Woolaston (1766–1828) in
1803.
A
• Information from the WebElements site
palmitate (hexadecanoate) A salt
or ester of palmitic acid.
palmitic acid (hexadecanoic acid)
A 16-carbon saturated fatty acid,
CH 3 (CH 2 ) 14 COOH; r.d. 0.85; m.p.
63°C; b.p. 390°C. Glycerides of
palmitic acid occur widely in plant
and animal oils and fats.
pantothenic acid A vitamin of the
*vitamin B complex. It is a constituent of coenzyme A, which performs a crucial role in the oxidation
of fats, carbohydrates, and certain
amino acids. DeÜciency rarely occurs
because the vitamin occurs in many
foods, especially cereal grains, peas,
egg yolk, liver, and yeast.
O
H
C
H 2
N
H
C
H 2
C
H 2
OH
H
OH
CH 3
C
H 3
O
O
Pantothenic acid
papain A protein-digesting enzyme
occurring in the fruit of the West Indian papaya tree (Carica papaya). It is
used as a digestant and in the manufacture of meat tenderizers.
paper chromatography A technique for analysing mixtures by
*chromatography, in which the stationary phase is absorbent paper. A
spot of the mixture to be investigated
is placed near one edge of the paper
and the sheet is suspended vertically
in a solvent, which rises through the
paper by capillary action carrying the
components with it. The components
move at different rates, partly because they absorb to different extents
on the cellulose and partly because of
partition between the solvent and
the moisture in the paper. The paper
is removed and dried, and the different components form a line of spots
along the paper. Colourless substances are detected by using ultrawww.AzShimi.ir www.AzShimi.com
PAGE (polyacrylamide gel electrophoresis) A type of *electrophoresis used to determine the size and
composition of proteins. Proteins are
placed on a matrix of polyacrylamide
gel and an electric Üeld is applied.
The protein molecules migrate towards the positive pole, the smaller
molecules moving at a faster rate
through the pores of the gel. The proteins are then detected by applying a
stain.
PAH Polyaromatic hydrocarbon. See
particulate matter.
palladium Symbol Pd. A soft white
ductile *transition element (see also
platinum metals); a.n. 46; r.a.m.
106.4; r.d. 12.02; m.p. 1552°C; b.p.
3140±1°C. It occurs in some copper
and nickel ores and is used in jewellery and as a catalyst for hydrogenation reactions. Chemically, it
does not react with oxygen at normal
temperatures. It dissolves slowly in
hydrochloric acid. Palladium is capable of occluding 900 times its own
volume of hydrogen. It forms few
simple salts, most compounds being
complexes of palladium(II) with some
palladium(IV). It was discovered by
William Woolaston (1766–1828) in
1803.
A
• Information from the WebElements site
palmitate (hexadecanoate) A salt
or ester of palmitic acid.
palmitic acid (hexadecanoic acid)
A 16-carbon saturated fatty acid,
CH 3 (CH 2 ) 14 COOH; r.d. 0.85; m.p.
63°C; b.p. 390°C. Glycerides of
palmitic acid occur widely in plant
and animal oils and fats.
pantothenic acid A vitamin of the
*vitamin B complex. It is a constituent of coenzyme A, which performs a crucial role in the oxidation
of fats, carbohydrates, and certain
amino acids. DeÜciency rarely occurs
because the vitamin occurs in many
foods, especially cereal grains, peas,
egg yolk, liver, and yeast.
O
H
C
H 2
N
H
C
H 2
C
H 2
OH
H
OH
CH 3
C
H 3
O
O
Pantothenic acid
papain A protein-digesting enzyme
occurring in the fruit of the West Indian papaya tree (Carica papaya). It is
used as a digestant and in the manufacture of meat tenderizers.
paper chromatography A technique for analysing mixtures by
*chromatography, in which the stationary phase is absorbent paper. A
spot of the mixture to be investigated
is placed near one edge of the paper
and the sheet is suspended vertically
in a solvent, which rises through the
paper by capillary action carrying the
components with it. The components
move at different rates, partly because they absorb to different extents
on the cellulose and partly because of
partition between the solvent and
the moisture in the paper. The paper
is removed and dried, and the different components form a line of spots
along the paper. Colourless substances are detected by using ultrawww.AzShimi.ir www.AzShimi.com