vitamins , co-enzymes and co-factors Flashcards
vitamins , co-enzymes and co factors
they are mainly organic but can contain inorganic components or co-factors
some work with/are part of enzymes
they promote biochemical reactions
water soluble examples include all vitamin B and vitamin c
Lipid soluble examples include vitamins A,D,E,K
most of the B vitamins are used in secondary metabolism
what is a co-factor
a co-factor is a substance whose presence is essential for the activity of an enzyme
Thiamine (Vitamin B1)
catalyses decarboxylation of alpha-keto acids , a feature of primary metabolism
they turn pyruvic -> acetaldehyde in glycolysis
pyruvic -> acetyl-CoA
helps metabolise carbohydrates
deficiency causes beriberi which is a neurological disorder
it is found in cereals , wheats , beans , nuts , eggs , yeasts and vegetables
Riboflavin ( Vitamin B2)
they catalyse dehydrogenation reactions
they are involved in redox reactions of c-c bonds
they are involved in the metabolism foods including liver , kidney, dairy products , eggs , yeast , meat and fresh vegetables
they promote healthy skin and vision
deficiency causes eye problems and skin disorders
niacin/nicotinic acid ( Vitamin B3)
as part of the NAD+ system , catalyses redox reactions of alcohols/carbonyl compounds
degradation of L-tryptophan -> niacin (B3)
needed for general metabolism , health of skin , nervous and digestive system
found in meats , fish , yeast , eggs , dairy , grains , nuts , legumes , roasted coffee
deficiency of vitamin B3 causes pellagra
- oral lessions , diarrhea , dermatitis and dementia
what is tryptophan
tryptophan is an alpha-amino acid used in the biosynthesis of proteins . it is essential in humans , meaning the body cannot synthesise it ; it must be obtained from the diet. tryptophan is a precursor for vitamin b3
pantothenic acid (vitamin B5)
is a part of co-enzyme A
synthesis of fatty acids , some peptides , phenylpropanoids , isoprenoids
involved in fat , carbs and protein metabolism
very widely distributed throughout foods - yeast , liver and cereals provide rich sources
deficiency is rare
vitamins B3,5,6 and biotin are thought to promote healthy hair and prevent hair loss
vitamin b6 ( pyridoxamine , pyridoxal phosphate and pyridoxine )
catalyses transamination and decarboxylations of amino acids
metabolism -> energy
in plants , it is used in biosynthesis of phenylpropanoids from amino acids
meat salmon nuts potatoes bananas and cereal are all options for getting vitamin B6
can be lost through cooking however , deficiency is usually caused by poor absorption
deficiency causes nervous disorders , skin rash , muscle weakness , anaemia
vitamin B12 (cobalamins)
Involved in synthesis of DNA, amino acids, fatty acids, one-C metabolism (methylations)
Needed to maintain nerve cells, RBC, genes
Microbial in origin; intestinal flora contribute towards human dietary needs.
Stored in the liver
Found in meat, shellfish, liver, dairy products and eggs
Deficiency causes pernicious anemia (inability to absorb the vitamin B12 needed to make enough healthy red blood cells).
Poor absorption of B12 is thought to be a complication of aging
Contains Co(III) coordinated to a corrin ring (R = CN is cyanocobalamin, most common form)
Vitamin B9 (folate)
Role: Tetrahydrofolate functions in one-C metabolism as a carrier of methyl, methylene or formyl groups
Involved in amino acid and nucleotide metabolism, red blood cell formation
Found in green veggies, yeast, liver, legumes, whole grains, some fruits
Deficiency can cause anaemia, neural tube defects in a foetus, cardiovascular problems in adults
Folate intake linked to reduced cardiovascular disease, colon cancer in women and depression in men
Relationship between one-C metabolism, B-vitamins and health
One-C metabolism (methylation) is a key reaction in formation of both primary and secondary metabolites in plants & animals, also involved in DNA repair and detoxification pathways
Elevated homocysteine levels in humans are an indicator (marker) of faulty one-C metabolism
Homocysteine (HCys) is made from methionine (L-Met), but much of the HCys must be cycled back to L-Met
Decreased formation of L-Met and SAM result in decreased methylation
Decrease in the methylation pathway is associated with increased risk of cardiovascular disease, Alzheimer’s disease and some cancers.
High HCys levels are also thought to be linked to increased production of reactive oxygen species that damage tissues
Adequate supply of folate (B9), B12 and B6 in diet is necessary to maintain proper HCys metabolism.
Biotin (Vitamin H): functions as a carboxyl group carrier
Found in eggs, liver, kidney, yeast, cereals, milk
Also produced by intestinal microflora
Deficiency is rare, but could lead to dermatitis and hair loss
Ascorbic acid (Vitamin C )
Antioxidant, strong reducing agent
Collagen synthesis, tissue repair, bones & teeth, immune system, iron absorption
Cannot be made by human body though animals can biosynthesize from glucose
Found in citrus fruits, cruciferous veggies, tomatoes, dark green leafy, berries, mangos, melons
Degraded by cooking
Deficiency causes scurvy, anaemia, depression, infection, tooth/gum problems, muscle deterioration, fragile bones, poor wound healing
