Biochemistry Group Presentation

8/3/2019 Biochemistry Group Presentation

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Some enzymes do not need any

additional components to show full activity. However,

others require non-proteinmolecules called cofactors to bebound for activity


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CoFactors

Often classified as inorganic substances that are required for, orincrease the rate of, catalysis.

Non-protein chemical compound .

Essential ions

Can either be metal ions or small organic molecules also knownas Coenzymes.

chemical teeth or helper molecules of enzymes .

Apoenzyme + cofactor = holoenzyme


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Apoenzyme

= inactive enzyme, without the cofactor= Without its respective coenzyme

= The enzyme (protein) component of the holozyme

Holoenzyme

= complete enzyme with cofactor= With the coenzyme

Precursors of coenzymes: B VITAMINS thiamine (B1)riboflavin (B2)nicotinamide
http://en.wikipedia.org/wiki/Apoenzymehttp://en.wikipedia.org/wiki/Holoenzymehttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nutrition.htmlhttp://en.wikipedia.org/wiki/Holoenzymehttp://en.wikipedia.org/wiki/Apoenzyme


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(cofactors can be divided into two broad groups)

Classification:

Organic Inorganic


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Such as flavin or heme often vitamins or are made from vitamins. Further divided into:

> Coenzymes = loosely-bond cofactors> Prosthetic groups = tightly-bond cofactors

= non protein coenzyme component

Such as metal ions Mg, Cu, Mn or iron-sulfur clusters


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Metal ion CoFactors

Usually transition metals that coordinate withenzyme-substrate complex.

Usually TRACE elements : Cu2+, Fe2+, Zn2+etc.. Calcium, Chromium and Iodine are the only

exceptions.

Inorganic Metal-activated or Metalloenzymes activators


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Also known as the common

COFACTORS

Iron (Fe 3+), manganese (Mn 2+),

cobalt (Co 2+), copper (Cu 2+), zinc(Zn 2+), selenium (Se 2+), and

molybdenum (Mo 5+)

The function of some enzymescannot be carried out if a metalion is not available


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METAL IONS ENZYMES containingCupric Cytochromeoxidase

Ferrous or Feric CatalaseCytochrome (via Heme)NitrogenaseHydrogenase

Magnesium Glucose 6-phosphateHexokinase

Manganese Arginase

Molybdenum Nitrate reductase

Nickel Urease

Selenium Glutathioneperoxidase

Zinc Alcohol dehydeogenase

Carbonicanhydrase


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Examples of some enzymes that require metal ions ascofactors:

cofactor protein Zn++ carbonic anhydrase

Zn++ alcohol dehydrogenase

Fe+++ or Fe++ cytochromes, hemoglobin

Fe+++ or Fe++ ferredoxin Cu++ or Cu+ cytochrome oxidase

K+ and Mg++ pyruvate phosphokinase


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Iron-Sulfur transfer

iron-sulfur clusters are complexes of iron and sulfur atomsheld within proteins by cysteinyl residues.

They play both structural and functional roles, includingelectron transfer, redox sensing, and as structural modules.


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CoEnzymes Highly organic molecules They must be regenerated :

In order to complete the catalytic cycle, thecoenzyme must return to its original state.

Can either be Prosthetic or loosely bound Cosubstrates.

Water-soluble vitamins are precursors of coenzymes.

Mostly derived from vitamins.


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VITAMINsource

COENZYME REACTIONMEDIATED

Thiamin (vitamin B 1) Thiaminepyrophosphate

2-carbon groups,alpha cleavage,decarboxylation inkrebs cycle

Niacin (vitamin B 3) NAD+ and NADP +

(nicotinamide)Electrons( oxidation-reduction)

Pyridoxine (vitaminB6)

Pyridoxal phosphate Amino/carboxylgroups

Lipoic acid lipoamide Acyl grouptransfer/electrons

Vitamin B 12 Methylcobalamin Acyl groups


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VITAMINS COENZYME REACTIONMEDIATED

Vitamin B 12 Cobalamine Hydrogen/ alkylgroups

Vitamin H Biotin CO 2carboxylasereactions.

Vitamin B 5 (pantothenic acid)

Coenzyme A Acetyl group/ otheracyl groups

Folic acid Tetrahydrofolic acid Methyl, formyl,methylene andformino groups.

Vitamin K Menaquinone Carbonyl groups/

oxidation-reduction of electrons.


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VITAMINS COENZYMES REACTION


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VITAMINS COENZYMES REACTIONMEDIATED

Vitamin C Ascorbic acid Oxidation/reductionof electrons.

Vitamin B 2(RIBOFLAVIN)

Flavinmononucleotide

(FMN)

Oxidation of substrates

Vitamin B 2(RIBOFLAVIN)

Flavin adeninedinucleotide (FAD)

Oxidation of substrates

Vitamin B 2(RIBOFLAVIN) CoEnzyme F420 Oxidation/reduction

Vitamin A 1Vitamin A 2

retinol,dehydroretinol

Oxidation/reduction.Transfer of lightenergy.


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Ion Examples of enzymes containingthis ion Cupric Cytochrome oxidase

Ferrous or Ferric Catalase

Cytochrome(viaHeme)Nitrogenase Hydrogenase

Magnesium Glucose 6-phosphatase Hexokinase

Manganese Arginase Molybdenum Nitrate reductase

Nickel Urease Selenium Glutathione peroxidase

Zinc Alcohol dehydrogenase

Carbonic anhydrase

DNA polymerase
http://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Cytochrome_oxidasehttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Catalasehttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Hemehttp://en.wikipedia.org/wiki/Nitrogenasehttp://en.wikipedia.org/wiki/Hydrogenasehttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Glucose_6-phosphatasehttp://en.wikipedia.org/wiki/Hexokinasehttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Arginasehttp://en.wikipedia.org/wiki/Molybdenumhttp://en.wikipedia.org/wiki/Nitrate_reductasehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Ureasehttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Glutathione_peroxidasehttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Alcohol_dehydrogenasehttp://en.wikipedia.org/wiki/Carbonic_anhydrasehttp://en.wikipedia.org/wiki/DNA_polymerasehttp://en.wikipedia.org/wiki/DNA_polymerasehttp://en.wikipedia.org/wiki/Carbonic_anhydrasehttp://en.wikipedia.org/wiki/Carbonic_anhydrasehttp://en.wikipedia.org/wiki/Alcohol_dehydrogenasehttp://en.wikipedia.org/wiki/Alcohol_dehydrogenasehttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Glutathione_peroxidasehttp://en.wikipedia.org/wiki/Glutathione_peroxidasehttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Ureasehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Nitrate_reductasehttp://en.wikipedia.org/wiki/Nitrate_reductasehttp://en.wikipedia.org/wiki/Molybdenumhttp://en.wikipedia.org/wiki/Arginasehttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Hexokinasehttp://en.wikipedia.org/wiki/Glucose_6-phosphatasehttp://en.wikipedia.org/wiki/Glucose_6-phosphatasehttp://en.wikipedia.org/wiki/Glucose_6-phosphatasehttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Hydrogenasehttp://en.wikipedia.org/wiki/Nitrogenasehttp://en.wikipedia.org/wiki/Hemehttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Catalasehttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Cytochrome_oxidasehttp://en.wikipedia.org/wiki/Copper

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Biochemistry Group Presentation