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The Chemistry of Protein

Food for Thought

Protein was named over 150 years ago after the Greek word proteios meaning "of prime importance."

Protein consists of carbon, hydrogen, oxygen, and nitrogen. The addition of nitrogen gives protein its unique distinction from carbohydrate and fat, along with establishing the signature name, amino acid. Much like simple sugars, which link together to form a complex carbohydrate (see What Is a Carbohydrate?), amino acids are the building blocks for the more complicated protein molecule.

Amino Acids: The Building Blocks of Protein

There are a total of 20 different amino acids, and depending upon the sequence in which they appear, a specific job or function is carried out in your body. Think of amino acids as similar to the alphabet—26 letters that can be arranged in a million different ways. These arranged letters create words, which then translate into an entire language. The arrangement of amino acids is your body's “protein language,” which dictates the exact tasks that need to be carried out. Therefore, proteins that make up your enzymes will have one sequence, whereas those that form your muscles will have a completely different one.


Proteins are compounds made of carbon, hydrogen, oxygen, and nitrogen and arranged as strands of amino acids.

Your Bod: The Amino Acid Recycling Bin

Your body continually gets the amino acids it needs from its own amino-acid pool and from a diet that meets your daily protein requirements. After you eat a food that contains protein, your body goes to work, breaking it down into the various amino acids. (Different foods yield different amino acids.) When the protein is completely dissected, your body absorbs the amino acids (resulting from your digested food) and rebuilds them into the sequence that you need for a specific body task. Your body is sort of like a recycling bin.


Amino (a-MEEN-o) acids are the building blocks for protein that are necessary for every bodily function

Let's take this amino acid talk a bit further. Out of 20 amino acids, 11 can actually be manufactured within your body. However, that means nine cannot be manufactured. You cannot function without each and every amino acid. It is “essential” that you get these nine from outside food sources. Therefore, they are appropriately called essential amino acids.

Essential Amino Acids Nonessential Amino Acids

Histidine Glycine
Isoleucine Glutamic acid
Leucine Arginine
Lysine Aspartic acid
Methionine Proline
Phenylalanine Alanine
Threonine Serine
Tryptophan Tyrosine
Valine Cysteine

Excerpted from The Complete Idiot's Guide to Total Nutrition © 2005 by Joy Bauer. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

To order this book visit the Idiot's Guide web site or call 1-800-253-6476.


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