Why does pepsin act only on proteid matter, and ptyalin only on starch and dextrins?
Of the first importance, however, is the proteid element in food.
The particular number of grains of proteid to be consumed per day is not of serious moment.
The percentage of proteid in grapes is particularly high for fruit.
See that the proportion of proteid is one part to four of carbohydrates and fats.
On the contrary, the proteid matter so introduced appears to be assimilated and utilized for the needs of the organism.
It is probable that a smaller quantity of proteid would have been enough if the fat and carbohydrates had been increased.
They can only utilize the proteid material elaborated from the products of proteolysis by other agencies.
Oysters and clams, which are generally eaten uncooked, are recommended by many authorities as valuable sources of proteid.
Nutrient ratio is the proportion of the sum of the carbo-hydrate and fat, compared with the proteid as 1.
1844, from French protéine, coined 1838 by Dutch chemist Gerhard Johan Mulder (1802-1880), perhaps on suggestion of Berzelius, from Greek proteios "the first quality," from protos "first" (see proto-) + -ine (2).
Originally a theoretical substance thought to be essential to life, further studies of the substances he was working with overthrew this, but the words protein and proteid continued to be used in international work on the matter and also for other organic compounds; the modern use as a general name for a class of bodies arose in German. The confusion became so great a committee was set up in 1907 to sort out the nomenclature, which it did, giving protein its modern meaning and banishing proteid.
proteid pro·te·id (prō'tē-ĭd)
A protein. No longer in scientific use.
protein pro·tein (prō'tēn', -tē-ĭn)
Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of chains of alpha-amino acids. Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary to the functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.
Any of a large class of complex organic chemical compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures, usually containing alpha helices and beta sheets as well as looping and folded chains. Enzymes, antibodies, and hemoglobin are examples of proteins.
Our Living Language : Proteins are the true workhorses of the body, carrying out most of the chemical processes and making up the majority of cellular structures. Proteins are made up of long chains of amino acids, but they don't resemble linear pieces of spaghetti. The atoms in these long chains have their own attractive and repulsive properties. Some of the amino acids can form bonds with other molecules in the chain, kinking and twisting and folding into complicated, three-dimensional shapes, such as helixes or densely furrowed globular structures. These folded shapes are immensely important because they define the protein's function in the cell. Some protein shapes fit perfectly in cell receptors, turning chemical processes on and off, like a key in a lock, whereas others work to transport molecules throughout the body (hemoglobin's shape is ideal for carrying oxygen). When proteins fail to take on their preordained shapes, there can be serious consequences: misfolded proteins have been implicated in diseases such as Alzheimer's, mad cow, and Parkinson's, among others. Exactly how proteins are able to fold into their required shapes is poorly understood and remains a fundamental question in biochemistry. See more at prion.