Nomenclature of Enzymes

Classes on the basis of reaction type and functional groups.For enzyme classes and subclasses arabic numbers are used.Oxidoreductase NAD(P) acceptor

1.1.1.1

CH-OH donor alkohol-dehydrogenase

Main enzyme classes:

1. Oxidoreductase 2. Transferase

3. Hydrolase 4. Lyase

5. Isomerase 6. Ligase

Main class: kind of reaction

Sub-class: donor group or the type of the reaction

Sub-sub-class: acceptor group or substrate

Serial number specifies the enzyme itself

e.g. 1.2.3.4 means: oxidoreductasesaldehyde group donoroxygen acceptoroxalate oxidase

Main classes:1. oxidoreductases2. transferases3. hydrolases4. lyases5. isomerases6. ligases

1.) Oxidoreductases1.X.1.Y: NAD or NADP acceptors = dehydrogenases

1.6.4.Y. NADPH H-donor (and S-S H-acceptor) = reductases

1.3.X.Y.O2 electron acceptor, H2O2 product = oxidases(except cytocrhome-oxidase: H2O)

Monooxygenases: 1 atom oxygen built in, another forms water

Dioxygenases: both oxygen atoms built in

Peroxidases: H2O2 or R-OOH degradation

Coenzymes of oxidoreductases may be:NAD, NADP, FAD, FMN, lipoate, ascorbate, DHB, cytochromes, iron-sulfur centres

2.) Transferases2.1.1. methyltransf. coenzyme: SAM = S-adenosylmethionine

(exceptionally betain, methyl-THF)2.1.2. C-1 units: methyl-, hydroximethyl-, formyl-, formimino-,

methylene-, methenyl-coenzyme: THF= tetrahydrofolate

2.2. ketogrouptransketolase: TPP, transaldolase

2.3.1. acyltransf.coenzyme: HS-CoA = coenzyme A

2.4. glycosyltransferases:. di-, oligo- and polysaccharide formation (synthases)active forms: UDP-sugar (UDP-glucuronate, PRPP)

2.6.1. aminotransferases:amino acid1 + oxo acid2 = oxo acid1 + amino acid2

2.7. Phosphotransferases = kinases donor: ATPacceptor OH-, COO--, NH2-, HPO4

2-, etc. 2.8.2. Sulfotr. = sulphate transfer

coenzyme: PAPS (phosphoadenosyl-phosphosulfate)

3.) Hydrolases (hydrolysing enzymes)3.1. esterases

carboxyl-, thiol-, phosphate-, sulphate ester hydrolysing3.2. glycosidases: oligo- és polysaccharide cleaving3.4. peptidases, proteases = protein degrading

4.) Lyases addition to double bonds or small molecule elimination4.1. 1.decarboxylases, coenzyme: PLP4.1.3. oxo acid lyases: citrate-synthase or lyase

4.2.1. Hydrolyases: water elimination or addition:fumarase, enolase, akonitase

4.6.1.1. adenylate-cyclase

5.) Isomerases5.1. Racemases and epimerases: one group position changed5.2. cis-trans isomerases5.3.1. aldo-keto isomerases (aldose-ketose)5.3.3. double bond position changers (unsaturated fatty acids)

6.) Ligases = synthetases: ATP, CTP, GTP requiring6.1.1. aminoacyl-tRNA synthetases6.2.1.acyl-CoA synthetases6.3.2. peptid synthetases e.g. glutathione = GSH6.3.5.acid amide producing with Gln donor (GMP, Asn)6.4. carboxylases, coenzyme: biotin

Vitamins: obligatory need for the living organisms for the life - the given creature can not produce, it has to eat-take part in enzyme catalysis, or they are hormons or other regulating factors.-small organic molecules

B-vitamins: 1,2,3,5,6,7,9,12 and vitamin C arewater soluble

A,D,E,K vitamins are lipid soluble

Coenzyme = loosely bound, easily dissotiated from the enzyme,taking part in catalysis, small organic moleculeNAD, NADP, CoA

Prosthetic group = strictly bound to enzymes, not dissociated, taking part in catalysis, small organic moleculeFAD, FMN, TPP, PLP, THF, DHB, biotin, cobalamine

Effect of alcoholism on the metabolism of vitamins

1.) gastroenteritis, diarrhoea → wrong absorption2.) steatohepatitis, cirrhosis → storing capacity of the liver is decreased

especially pyridoxal, folate, cobalamin3.) competition with acetaldehyde on transport protein → pyridoxin

degradation is increased4.) iron absorbtion increased → iron deposits in liver, ROS formation

Coenzymes of energy producing pathways:NAD, FAD, FMN, TPP, CoA, (PLP), biotin

Any of them is missing → carbohydrate- lipid-, amino acid degradation is decreased → ATP shortage → fast multiplicatingcells (intestine, skin, blood cells) and big energy requireing organs(nervous system, heart, muscles) can not work properly

Vitamins taking part in amino acid and nucleotid metabolism pyridoxin, folate, cobalamin

In their deficiency the metabolism of amino acids and synthesis ofnucleotides, therefore synthesis of nucleic acids (DNA, RNA) is improper mainly in fast replicating cells:

blood cells, enterocytes, skin, mucous membranes

Excess water soluble vitamins are excreted by kidney, some of them are stored in liver:folate, cobalamin (6 years), pyridoxin (2 month).

Even pharmacological doses do not cause poisoning or overdosage, exceptvit. B3 and B6.

Lipid soluble vitamins absorbed and transported together with lipids.

Pharmacological doses cause poisoning of vitamin A or D.

Vitamin E has many adventageous characteristics, no overdosing

Vitamin B1 = tiamin → TPP= thiamin-pyrophosphate prosthetic group

Function: oxidative decarboxylation in enzymes: PDHC, αKGDHC,and transketolase

Deficiency: no aerob glucose degradation, citric acid cycle, amino acid degradation leading to ATP-shortagepentosephosphate pathway can not work, NADPH-deficiency

Low grade deficiency in elderly and restricted, poor diet:loss of appetite, constipation, depression, peripheral neuropathy,irritability, fatigue

Moderate severe deficiency in chronic alcoholists = Wernike-Korsakoff- syndrome: mental confusion, ataxia (missing movementcoordination), ophtalmoplegia (lower eye movement capacity)

Severe deficiency = beri-beri: in alcoholists, in populations who eat onlypolished rice: muscle atrophy (disappearance), heart failure

Demand increased: carbohydrate rich food, fever, trauma, pregnancy, lactation, tea- and coffee consumers

Source: every natural organic food except polished rice, white flour,refined sugar. It is found in the cover of the seedsof cereals.

Vitamin B-2 = riboflavin → FAD, FMN prost. gr.

Producers: plants, bacteriaStores: yeast, liver, kidney, egg, milk

Function: some dehydrogenases and reductases, all oxidasesE.g. succinate deh., mt. glycerol-3-P deh., electrontransport prot.

acyl-CoA deh. dihydrolipoyl deh. glutathione red., NADH deh., amino acid oxidases. xanthine oxidase,cytochrome P450 red., pyruvate deh., ketoglutarate deh.

Deficiency signs in chronic alcoholists: (inflammations)angular cheilitis (lips), glossitis (tongue), stomatitis (mouth), photophobia, scaly dermatitis

Niacin, nicotinic acid, nicotinamide →vitamin B3

NAD, NADP

Not really a vitamin, we can synthesize it from tryptophan, but not enough. Synthesis needsTrp, pyridoxin, riboflavin, iron.

Sourses: lean meat, oily seeds, legumes, liver, fish(in maize Trp is scarce)

Deficiency in starving elderly, alcoholists: pellagra (= rough skin) 4 D symptoms: dermatitis, dementia, depression, diarrhoea and other mucous membranes’ inflammation in GI,and GU tract

Function:NAD: dehydrogenases’ characteristic coenzymeNADPH: reductases’ characteristic coenzyme

Demand increased: pregnancy, lactation, chronic illness

Pantothenic acid = vit. B5 → HS-CoA, ACP

Function: acyl-transferases, synthases, synthetasescarboxyl-group joins to it by thioesther bond.In carbohydrate, lipid, cholesterol, amino acid metabolism > 70 enzyme

Source: every originally living organism, especially liver, meat, milk,egg, legumes, mushrooms, fish, fully ground cereals

Sensitive for acids, alkalines and heatDeficiency signs: alone can not occur, just together with other vitamin B types

Pyridoxine, pyridoxal, pyridoxamin → pyridoxal phosphate =vit. B6 PLP

Function:Glycogen phosphorylase (here the bigest amount)

Amino acid metabolism:1. transaminases: Gly,Ala, Val, Leu, Ile, Tyr, Cys, Glu, Asp,

ornithine2. amino acid decarboxylases: noradrenalin, dopamin, adrenalin,

serotonin, hisztamin, GABA synthesis3. hem synthesis (for hemoglobin, myoglobin, cytochromes)4. sfingolipid synthesis (for membranes)5. Ser, Thr, Cys, Gly metabolism dehydratases, aldolases,

desulfinases, synthases and lyases, cleavage enzyme6. NAD(P) synthesis

Deficiency signs:Irritability, depression, peripheral neuropathy, seizures,

microcytic anaemia, glucose intolerance,thrombosis, cardiovascular signs

Source:meat, vegetables, fully ground cereals, egg yolk

Demand increase: lactation, pregnancy, age, oral contraceptivesconsumers, protein rich diet

Folate = folic acid = vit. B9 → THF = H4F = tetrahydrofolate

Function:Ser, Gly, His, Trp, choline degradationMet, dTMP, purin ring synthesismethyl-, methylene, methenyl-, formimino-, formyl-group transfer

Source:Every fresh, not heated, originally living food (‘cause heat sensitive)= fresh fruits, vegetables

Demand increased: lactation, pregnancy

Cause of deficiency: intestinal diseases, certain drugs, improper dietSigns of deficiency: macrocytic anemia, thrombosis, leucocyte

number decreased

Cobalamin = vit. B12 adenosyl-cobalamin, methyl-cobalamin

Function: methyl-THF, methyl-Cblhomocystein methionin

L-methylmalonyl-CoA succinyl-CoASource: exclusively bacteria can synthesize,

found in every animal and human cellsnot found in plants (strict vegetarians are in danger)

Deficiency signs:1.) blood cells pruduction decreased, in fast multiplicating tissues

nucleotides, nucleic acids are not producedmegaloblastic anaemia, anaemia periniciosa

2.) neurologic signs: acidosis, abnormal myelin sheat formationDeficiency can be: because of hereditary transporter defects, or

aquired: gut diseases, anacidity, antibodies

Biotin = vitamin B7 biotin

Function:Coenzyme of carboxylases : gluconeogenesis/citric acid cycle

anaplerotic, lipid synthesis, amino acid degradation

Source: nuts, egg, chocolate…Every living organism contains a little,

gut bacteria synthesize

Deficiency signs:depression, hallucination, dermatitis, muscle pain

Cause of deficiency:exteme malabsorption, raw egg white regular consumers

Ascorbic acid = vitamin C Ascorbic acid

Function:- in collagen Lys and Pro hydroxilation, collagen stabilization- adrenal gland: adrenalin and corticosteroid synthesis- nervous system: noradrenalin synthesis- reducing material: Fe3+ (absorption elevated), A- and E-vitamins

(antioxidant effect)- folic acid absorption increased

Source: fresh plants (It is degraded during heating or storage).

Deficiency signs:Scurvy: pinpoint hemorrhages, bruising, osteoporosis (collagen loss)

teeth loss, anaemia (iron deficient), wound healing impaired,muscle weakness

vitamin K = menaquinone, phylloquinonefrom animals, from plants

Function:in liver gamma-carboxylation of Gln in blood coagulation proteins (necessary for membranebinding during blood coagulation)

Deficiency signs: hemophylia

Cause of deficiency:lipid malabsorption because of pancreas, bile or intestinal diseases/ dysfunctionqumarin overdosage, newborn state(not enough in milk)

Vitamin deficiency often occurs in average population:folate, cobalamin, pyridoxin

Vitamin deficiency can occur in case of improper diet, alcoholists: thiamin, riboflavin, niacin, ascorbate, phyto/menaquinonsVitamin deficiency occurs only in extreme starvation or severe gut

diseases: panthotenic acid, biotin

Heat sensitives: folate, ascorbate, thiamin, panthotenateLight sensitive: riboflavin (B2-vit)Absorption complicated, problematic, found only in animals: vit. B-12Some medicines inhibit their absorption, speed their degradation or

antagonists: riboflavin, niacin, pyridoxin, vitamin K, folate

Vitamins alone are not enough, the proper enzyme action requires minerals and amino acids (in proper amount and ratio) as well.