Xray Source

Single crystal

Single crystal computerized calculation

Diffraction pattern


by computerized calculation

Diffraction pattern


Electron density map

Electron density map

Structure model

FIGURE 7.20 X-ray Crystallography

A) As light passes through an object, the light waves are distorted from their original pathway. Using a lens allows the distorted light waves to be refocused into an image of the object. B) X-rays are also distorted when they pass through an object. The structure of the proteins within a single crystal dictates the pattern in which the X-rays are diffracted. Moving the crystal around alters the pattern in which the X-rays are diffracted, and all the different patterns can be combined into one to form a model of the protein's actual structure.

Organic Cofactors and Vitamins compound

Active form/Cofactor

Vitamins that are enzyme cofactors or their precursors

Vitamin A = Retinol Vitamin B1 = Thiamine Vitamin B2 = Riboflavin

Vitamin B3 = Niacin (refers to nicotinamide and/or nicotinic acid)

Vitamin B5 = Pantothen ic acid

Vitamin B6 = Pyridoxine, pyridoxal, or pyridoxamine Vitamin B12 = Cobalamin

Biotin (a B vitamin) Folic acid (a B vitamin)

Vitamin K

Vitamin K1 = Phylloquinone Phylloquinone

Vitamin K2 = Menaquinone Menaquinone

Vitamin K3 = Menadione Menaquinone

Vitamins that are not enzyme cofactors or their precursors

Retinaldehyde Thiamine pyrophosphate Flavin adenine dinucleotide Flavin mononucleotide Nicotinamide adenine dinucleotide

Nicotinamide adenine dinucleotide phosphate

Coenzyme A 4'-Phosphopantetheine Pyridoxal phosphate

Methyl Cobalamin Deoxyadenosyl Cobalamin Biotin


Vitamin A = Retinol Vitamin C = Ascorbic acid Vitamin D = Ergocalciferol (D2) or Cholecalciferol (D3)

Vitamin E = Tocopherol

Cofactors that are not vitamins (i.e. can

Retinoic acid Ascorbic acid Calcitriol

Tocopherol be made by animals)

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