A manual of practical hygiene for students, physicians, and health officers / By Charles Harrington.

  • Harrington, Charles, 1856-1908.
Date:
1914
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene for students, physicians, and health officers / By Charles Harrington. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    and a coagulum on heating which is easily soluble in very dilute acids. On hydrolysis they yield a large number of amiuo-acids among which the basic ones predominate. {g) Protamines. Simpler polypeptides than the proteins included in the preceding groups. They are soluble in water, uncoagulable by heat, have the property of precipitating aqueous solutions of other proteins, possess strong basic properties, and form stable salts with strong mineral acids. They yield comparatively few amino-acids, among which the basic amino-acids greatly predominate. II. Conjugated Proteins. Substances which contain the protein molecule united to some other molecule or molecules otherwise than as a salt. (a) Nucleoproteins. Compounds of one or more protein molecules with nucleic acid. (6) Glycoproteins. Compounds of the protein molecule with a sub- stance or substances containing a carbohydrate group other than a nucleic acid. (c) Phosphorproteins. Compounds of the protein molecule with some, as yet undefined, phosphorus-containing substance other than a nucleic acid or lecithins.^ (r?) Hsemoglobins. Compounds of the protein molecule with hema- tin or some similar substance. (e) Lecithoproteins. Compounds of the protein molecule with lecithins (lecithans, phosphatides).. III. Derived Proteins. 1. Primary Protein Derivatives. Derivatives of the protein molecule apparently formed through hydrolytic changes which involve only slight alterations of the protein molecule. (a) Proteins. Insoluble products which apparently result from the incipient action of water, very dilute acids, or enzymes. (h) Metaproteins. Products of the further action of acids and alka- lies whereby the molecule is so far altered as to form products soluble in very weak acids and alkalies, but insoluble in neutral fluids. This group will thus include the familiar acid proteins and alkali proteins, not the salts of proteins with acids. (c) Coagulated proteins. Insolul)l(' ])roducts will result from (1) the action of heat on their solutions or (2) the action of alcohols on the ]>rotein. 2. Secondary Protein Derivatives.^ Products of the further hydro- lytic cl(«ivage of the protein molecule. f'/j Proteoses. Soluble in water, nncoagulated by heat, and pre- ci[>itated by saturating their solutions with ammonium or zinc sulphate. ' The ncciimiilated chemical evirlcnce diHtinctly points to the propriety of cla-isify- inpf the [>hi«ptioproteins a« conji](?ate<l compoiinrlH, i. e,, tliey are pomibly esters of some plioHfihoric acid or acirls and protein. ' The U-rm scondarj' liydrolytic derivatives is used because the formation of the primary derivatives iisnally precedes the formation of these secondary derivatives. ^' As tiiiis defined, this term does not strictly cover all the firotein derivatives com- monly called proteoses, e. i/., hetero[irotcose and dyiiroteose.