enzyme cofactors_and_vitamins
Upcoming SlideShare
Loading in...5
×
 

enzyme cofactors_and_vitamins

on

  • 111 views

 

Statistics

Views

Total Views
111
Views on SlideShare
111
Embed Views
0

Actions

Likes
0
Downloads
4
Comments
0

0 Embeds 0

No embeds

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

 enzyme cofactors_and_vitamins enzyme cofactors_and_vitamins Presentation Transcript

  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1 Chapter 20 Enzymes and Vitamins 20.6 Enzyme Cofactors and Vitamins
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2 Enzyme Cofactors  A simple enzyme is an active enzyme that consists only of protein.  Many enzymes are active only when they combine with cofactors such as metal ions or small molecules.  A coenzyme is a cofactor that is a small organic molecule such as a vitamin.
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3 Enzyme Cofactors (continued)
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 4 Function of Coenzymes  A coenzyme prepares the active site for catalytic activity.
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5 Metal Ions as Cofactors Many active enzymes require a metal ion. For example, Zn2+ , a cofactor for carboxypeptidase, stabilizes the carbonyl oxygen during the hydrolysis of a peptide bond.
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 6 Some Enzymes and Their Cofactors
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7 Learning Check Identify each enzyme as 1) a simple enzyme 2) an enzyme that required a cofactor A. requires Mg2+ for hydrolysis of phosphate esters B. requires vitamin B3 to transfer an acetyl group C. is active with four polypeptide subunits
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8 Solution Identify each enzyme as 1) a simple enzyme 2) an enzyme that required a cofactor 2 A. requires Mg2+ for hydrolysis of phosphate esters 2 B. requires vitamin B3 to transfer an acetyl group 1 C. is active with four polypeptide subunits
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 9 Water-Soluble Vitamins Water-soluble vitamins are  soluble in aqueous solutions  cofactors for many enzymes  not stored in the body
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Descriptions of Water-Soluble Enzymes 10
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11 Thiamin (Vitamin B1) Thiamin  was the first B vitamin identified  is part of the coenzyme thiamin pyrophosphate (TPP)  is used to decarboxylate α-keto carboxylic acids  has a recommended daily allowance (RDA) of 1.2 mg; deficiencies include fatigue, poor appetite, weight loss, nerve degeneration, and heart failure
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 12 Riboflavin (Vitamin B2) Riboflavin  is found in the coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN)  is needed for good vision and healthy skin  has an RDA of 1.2–1.8 mg; deficiencies include dermatitis, dry skin, tongue inflammation, and cataracts
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 13 Niacin (Vitamin B3) Niacin  is part of the coenzyme nicotinamide adenine dinucleotide (NAD+ ) involved in oxidation–reduction reactions  has an RDA of 14–18 mg  deficiency can result in dermatitis, muscle fatigue, and loss of appetite
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 14 Pantothenic Acid (Vitamin B5) Pantothenic acid  is part of coenzyme A needed for energy production  is involved in glucose and cholesterol synthesis  has an RDA of 5 mg  deficiency can result in fatigue, retarded growth, cramps, and anemia
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 15 Pyridoxine (Vitamin B6) Pyridoxine and pyridoxal are  two forms of vitamin B6, which are converted to the coenzyme pyridoxal phosphate (PLP)  required in the transamination of amino acids and decarboxylation of carboxylic acids  has an RDA of 1.3–2.0 mg; deficiency may lead to dermatitis, fatigue, and anemia
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 16 Cobalamin (Vitamin B12) Cobalamin  consists of four pyrrole rings with a Co2+  is a coenzyme for enzymes that transfer methyl groups and produce red blood cells  has an RDA of 2.0–2.6 μg  deficiencies are pernicious anemia, nerve damage, and malformed red blood cells
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 17 Ascorbic Acid (Vitamin C) Vitamin C  is required in collagen synthesis and healing of wounds  has an RDA of 60–95 mg  deficiencies are scurvy, weakened connective tissue, slow-healing wounds, and anemia
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Biotin Biotin  is a coenzyme for enzymes that transfer carboxyl groups  has an RDA of 30µ g  deficiencies include dermatitis, loss of hair, fatigue, and anemia 18
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 19 Folic Acid (Folate) Folic acid (folate)  consists of pyrimidine, p-aminobenzoic acid, and glutamate  forms the coenzyme THF used in the transfer of methyl groups and is involved in the synthesis of nucleic acids  has an RDA of 400 µ g  deficiencies are abnormal red blood cells, anemia, and poor growth
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 20 Folic Acid (Folate) (continued)
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 21 Fat-Soluble Vitamins Fat-soluble vitamins are  vitamins A, D, E, and K  soluble in lipids but not in aqueous solutions  stored in the body  important in vision, bone formation, antioxidants, and blood clotting
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 22 Retinol (Vitamin A) Vitamin A  is needed for retinol (vision); synthesis of RNA  has an RDA of 800 µ g  deficiencies include night blindness, immune system repression, and slowed growth
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 23 Cholecalciferol (Vitamin D) Vitamin D (D3)  is synthesized in skin exposed to sunlight  regulates the absorption of phosphorus and calcium during bone growth  has an RDA of 5–10 μg  deficiency includes weakened bones
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 24 Tocopherol (Vitamin E) Vitamin E  is an antioxidant in cells  may prevent the oxidation of unsaturated fatty acids  is found in whole grains and vegetables  has an RDA of 15 mg  deficiencies are hemolysis and anemia
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 25 Menaquinon (Vitamin K)  Vitamin K1 in plants has a saturated side chain.  Vitamin K2 in animals has a long unsaturated side chain.  Vitamin K2 is needed for the synthesis of zymogens for blood clotting.  Vitamin K has an RDA of 90– 120 μg.  Deficiencies are prolonged bleeding time and bruising
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 26 Learning Check Identify each of the following as a water-soluble vitamin (WS) or fat-soluble vitamin (FS). A. folic acid B. retinol (vitamin A) C. vitamin C D. vitamin E E. niacin
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 27 Solution Identify each of the following as a water-soluble vitamin (WS) or fat-soluble vitamin (FS) WS A. folic acid FS B. retinol (vitamin A) WS C. vitamin C FS D. vitamin E WS E. niacin
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 28 Learning Check Identify the vitamin associated with each 1) riboflavin (B2) 2) vitamin A 3) vitamin K 4) vitamin D 5) ascorbic acid A. collagen formation B. part of the coenzymes FAD and FMN C. absorption of phosphorus and calcium in bone D. vision E. blood clotting
  • General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 29 Solution Identify the vitamin associated with each 1) riboflavin (B2) 2) vitamin A 3) vitamin K 4) vitamin D 5) ascorbic acid 5 A. collagen formation 1 B. part of the coenzymes FAD and FMN 4 C. absorption of phosphorus and calcium in bone 2 D. vision 3 E. blood clotting