CHEM 4420: Glycolysis Part II (Lecture 4)

Vitamin B7 = (chemical name) + (active form)

Biotin / biocytin

Important structures on biotin/biocytin:

Carboxylation site on NH group opposite long hydrocarbon chain (“tether”) which connects to lysine group on protein. Once the N is carboxylated, the flexibility of the tether allows the carboxyl group to be shuttled to transcarboxylase subunit on protein. Acts as a mobile carboxyl group carrier

Vitamin B8 = (chemical name) + (active form)

Inositol / inositol

What is vitamin B8 responsible for?

Promotes cellular growth. Adipose tissue (fat tissue) signaling; inhibits mitochondrial fission by inhibiting AMPK, a kinase which promotes mitochondrial biogenesis. Being studied as a therapeutic treating variety of ailments

What are the risks of vitamin B8 deficiency?

alopecia, eczema, constipation, hyperlipidemia, myalgia/mypopathy, intestinal lipodystrophy

Vitamin B9 = (chemical name) + (active form)

Folic acid + tetrahydrofolate (THF)

What purpose does vitamin B9 serve?

It is a 1-C unit donor. H2C- units are housed in its structure and shuttled. Important for purine and thymidine synthesis

Significant structures in vitamin B9

Pteridine ring, vitamin B10, glutamic acid

Vitamin B10 facts:

Involved in tetrahydrofolate synthesis

Vitamin B11 facts:

Keratolytic (break down outer layers of skin) and anti-inflammatory

Description of vitamin B12 structure:

Pyrrole subunits and a relatively flexible, not totally planar corrin ring; forms a coordination complex with Co. Only stable metal-carbon bond! Stirrup formation

What is a corrin ring?

Similar to a porphyrin ring like in hemoglobin, but in vitamin B12 and with a methylene bridge removed

RDI of vitamin B12:

2\.4 mcg

Vitamin C =

Ascorbic acid

What evidence suggests that vitamin C may be a “cure” for the common cold?

Immune cells (neutrophils) destroy bacterial cell walls by releasing oxidants then engulfing them. Immune cells isolated within a medium with bacteria and vitamin c vs. a medium without bacteria and vitamin C absorb more vitamin C than the latter. Immune cells in infected plates absorbed more vitamin C. Since vitamin C is a strong reducing agent, may protect immune cells from their own oxidant attack.

RDI of folate:

500 micrograms per day

What are some medical benefits from eating sufficient (or even increased) levels of folate?

Decreased breast cancer risk in women, decreased blood pressure

Fat-soluble vitamins are all ____- based

Isoprenoid

What is vitamin A important for?

Vision, growth, cell-cell communication, reproduction, immune system

RDI of vitamin A:

900 mg

How is retinal attached to opsin to form rhodopsin in the eye?

The retinal is joined to a lysine residue on the opsin backbone by a Schiff base

Vitamin D =

Cholecalciferol

Vitamin D is often called a pro-

hormone: acts with PTH and calcitonin which adjust Ca2+, phosphorus levels

What is the chemical precursor to vitamin D?

7-dehydrocholesterol

What is the major circulating form of vitamin D in the body?

25-hydroxyvitamin D3

What is the most active form of vitamin D in the body?

1,25 dihydroxyvitamin D3

Why don’t all people see color the same way?

Tristimulus system of vision

RDA of vitamin D:

20 mcg

What is an example of “chemistry on a tether” besides vitamin B7?

Lipoic acid - an acyl group carrier coupling group transfer with e- transfer. Ring strain is key to its functionality