Chapter 4

Chapter 4 - b. Why is this important? i. Most combinations...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: b. Why is this important? i. Most combinations of and are no allowed because of steric clashes ii. Certain combinations of and are very stable 1. For example: a. The alpha helix has the same combination of and 3. Nomenclature naming peptides a. Amino Acid 1 Amino Acid 2 = dipeptides b. Amino Acid I Amino Acid 2 Amino Acid 3 = tripeptides c. 4-50 amino acids = polypeptides d. Greater than 50 amino acids = proteins i. Example 1: Gly-Ala = glycylalanine 1. The first amino acid gets the yl ending while the second amino acid remains the same ii. Example 2: Asp-Gly-Ala = aspartyl-glycyl-alanine iii. Example 3: A Billion Dollar dipeptide a. L-aspartyl-L-phenylalanyl methyl ester Chapter 4: Protein Architecture Levels of structural organization a. Primary sequence i. The sequence of amino acids in a protein b. Secondary Structure i. The path in 3-D space that the backbone atoms occupy ii. It is important to note that it EXCLUDES the R-Groups 1. Example: -Helix c. Tertiary structure i. The entire 3-D structure of the protein this includes contributions from the R- groups 1. Example: A globular protein d. Quaternary structure: i. Not all proteins have a quaternary structure, which is the organization of proteins with greater than one polypeptide chain (subunits) 1. Example: Hemoglobin More Details about: a. Primary Structure: i. It determines all higher order structures ii. This is what makes each protein unique 1. For example: Consider a 60 reside protein with 20 different amino acids. It is a relatively small protein. However, there is a possible combination of 20 60 which is approximately 10 79 . In real life, there is not this many combinations. b. Secondary Structure i. Alpha helix 1. Linus Pauling discovered this structure in 1951 a. The alpha helix is a rod-like backbone that is coiled around a central helix i. If you look at an alpha helix down the center, the R groups point out and away and are parallel to the helix ii. Every six R groups will be on the same face of the helix iii. Water must be exclude from the inside of the alpha helix or it will distort the helix. Its a good thing the atoms take up shape and exclude water iv. The helix has a net dipole b. Stabilized by H bonding between components of the polypeptide backbone i. H bonding takes place between m and m+4 residues c. 10-14 resides in length one complete turn of the alpha helix is...
View Full Document

Page1 / 5

Chapter 4 - b. Why is this important? i. Most combinations...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online