Advanced Concepts

Peptides can have biological activity. Hormones such as insulin, glucagons, corticotropin, oxytocin, bradykinin, and thyrotropin are examples of peptides (9-40 amino acids long) with strong biological activity. Several antibiotics such as penicillin and streptomycin are also peptides.

sickle cell anemia is a well-known example. Replacement of a soluble glutamine residue with a hydrophobic valine at the sixth residue changes the nature of the protein so that it packs aberrantly in corpuscles and drastically alters cell shape. Minor changes in primary structure can have such drastic effects because the amino acids must often cooperate with one another to bring about protein structure and function.

Amino acid 1 Amino acid 2

Amino acid 1 Amino acid 2

Peptide bond

+ amino acid 3

Peptide bond

+ amino acid 3

Interactions between amino acid side chains fold a protein into predictable configurations. These include ordered beta or beta-pleated sheets and less ordered alpha helices or random coils. The alpha helix and beta sheet structures in proteins (Fig. 3-5) were first described by Linus Pauling and Robert Corey in 1951.2-5 This level

H3N'

"C

Was this article helpful?

0 0
Delicious Diabetic Recipes

Delicious Diabetic Recipes

This brilliant guide will teach you how to cook all those delicious recipes for people who have diabetes.

Get My Free Ebook


Post a comment