Albus, white), an organic substance typical of a group of bodies (albumins or albuminates) of very complicated chemical composition.
The vegetable kingdom is the original source of albuminous substances, the albumins being found in greatest quantity in the seed.
The chemistry of the albumins is one of the most complicated and difficult in the whole domain of organic chemistry.
The albumins contain in all cases the elements carbon, hydrogen, nitrogen, sulphur and oxygen; their composition, however, varies within certain limits: C= 50-55%, H = 6.9-7'.3%,N = 15-19%,S =0.32.4%7 0=1 92 4%, General char- crystallized albumin is C = 51.48%, H = 6.76%, N= acters.
All albumins are laevo-rotatory; and on incineration a small amount of inorganic ash is invariably left.
A remarkable change occurs when many albumins are boiled with water, or treated with certain acids, their solubility and general characters being entirely altered, and the fluid becoming coagulated.
Albumins are generally detected by taking advantage of this property, or of certain colour changes.
Boiling with dilute mineral acids, or baryta water, decomposes albumins into carbon dioxide, ammonia and fatty aminoand other acids.
The complexity of composition militates in a great measure against a rational classification of albumins by purely chemical considerations.
Albumins proper: characterized by having colloidal solutions.
Albumins: serum-albumin, egg-albumin, lact - albumin.
Phosphorus containing albumins (nucleo-albumins), caseins, vitellines, nucleo-albumins of the cellprotoplasm, mucoid nucleo-albumins.
Transformation products of the albumins proper.
(I) Acid-albumins, alkali albuminates.
(3) Halogen-albumins, oxyprotein, oxyprotsulphonic acid, &c.
Albumins (as classified above) are soluble in water, dilute acids and alkalies, and in saturated neutral salt solutions; they are coagulated by heat.
Plant albumins or phyto-albumins have been chiefly investigated in the case of those occurring in seeds; most are globulins,.
Fibrin, produced from fibrinogen by a ferment, is a jelly-like substance, coagulable by heat, alcohol, &c. The muscle-albumins include " myosin " or paramyosinogen, a globulin, which by coagulation induces rigor mortis, and the closely related " myosinogen " or myogen; myoglobulin and myoalbumin are also found in muscles.
The nucleo-albumins or phospho-globulins are insoluble in water and acids, but soluble in alkalies, and have an acid reaction.
Histones are a class of albumins soluble in water and acids, but essentially basic in character; hence they are precipitated by alkalies.
The protamines are a wellcharacterized class of albumins found in the ripe spermatozoa of fishes.
The primary products of the dissociation of albumins are the albumoses, characterized by not being coagulable by heat, more soluble than the albumins, having a far less complex composition, and capable of being " salted (7) out " by certain salts, and the peptones, similar to albumoses but not capable of being " salted out "; moreover, peptones are less complex than albumoses.
These substances are combinations of one or more albumins with a radical of an essentially different nature, termed by Kossel a " prosthetic group."
" Nucleo-proteids," constituents of the cell-nucleus, are combinations of albumins and nucleic acid; they always contain iron.
Chemically they resemble the albumins, being split up by acids or ferments into albumoses, peptones and amino-acids, forming salts, and giving N =C6 1 The pyrimidin ring is numbered 2C "C5.
Colouring matters derived from albumins include the " melanins " (Gr.
These soluble salts combine with the albumins in the body, and are deposited as minute granules of silver albuminate in the connective tissue of the skin papillae, serous membranes, the intima of arteries and the kidney.