Biochem Of Met, Block 2, # 10: Nitrogen Met, Amino Acid Ii

Front 1

Which amino acids are "essential" and what does that mean?

Back 1

essential amino acids can't be manufactured by the body.

Pvt Tim Hall

non-essentials = AAA GS
(asparagine, aspartate, alaine, glutemate, serine)

Phenylalanine, isoleucine, threonine, tryptophan, histidine, arginine, leucine, lysine.

Front 2

what pathways provide the source for amino acid synthesis precursors?

Back 2

pentose phosphate, CAC, and glycolysis

Front 3

Alpha ketogluterate as a starting place: what kinds of amino acids can be formed?

Back 3

alpha ketogluterate becomes glutemate, which in turn can become proline, argenine, and glutamine.

First reaction is to go from alpha ketogluterate to glutamine. This can be done

Front 4

Alpha ketogluterate to glutemate: how can this be made?

Back 4

2 ways: a transaminase and glutemate dehydrogenase reaction.

transaminase: start with alphaketogluterate, add in ASPARTATE as a nitrogen donor, use transaminase, form oxaloacetate and glutemate.

Glutemate dehydrogenase: use NADPH and somehow get a nitrogen donation to become glutemate.

Front 5

Glutemate to glutamine: what's our enzyme?

Back 5

Glutamine synthase! This is from the urea lecture

Note that the reverse reaction uses glutaminase

Front 6

glutemate to proline:

Back 6

Reduced and cyclized version of glutemat = PROLINE

has to go through an intermediate that was seen in the catabolism lecture (glutemate semialdehyde), using glutemate semialdehyde dehydrogenase.

Front 7

glutamate to argenine:

Back 7

this requires 2 intermediate steps: converstion to glutemate semialdehyde (using glutemate semialdehyde dehydrogenase), and then conversion to ornathine.

This is put into the urea cycle going forwards 3 steps instead of backwards 1 to make argenine.

note that in cells that grow a lot, the argenine produced from the urea cycle is insufficient and it becomes an essential amino acid.

Front 8

Oxaloacetate as a precursor: what's formed?

how?

Back 8

mnenomic: MALT

we need to worry about asparagine. Essentials are also made (methionine, lysine, threonine)

Need to go from oxaloacetate to asparatate to asparagine. Asparatate is made by transamination

asparate to asparagine = aspargine synthase!

Front 9

Pyruvate as a precursor: what can we form?

How do we form our one(s) of interest?

Back 9

Mnemonic: vila

Alanine is our only non-essential. rest include:

valine, leucine, isoleucine.

pyruvate to alanine via alanine aminotransferase (ALT), important in movement between liver and muscles.

Front 10

3 PG as a precursor:

Back 10

forms SERINE, which can become glycine and cystein.

Front 11

Serine and glycine: how do we make it?

Back 11

don't need enzymes, just order.

oxidation, transamination, and phosphate hydrolysis get you to serine.
to get glycine, need a hydroxymethyl transferase.

Front 12

How do we make cysteine?

Back 12

start at HOMOCYSTEINE, add serine and make
cystathione
break into cysteine and alpha ketobutyrate

Front 13

Catecholamine synthesis: what do we start with and in what order do we go?

how can you tell something a catecholamine?

Back 13

tyrosine! Note that it has a phenyl ring with 1 -OH group. Catecholamines have 2 adjacent -OH groups on that ring.

Go in the order:
dopa
dopamine
norepinephine
epinephrine.

Front 14

What's the reaction from tyrosine to dopa? What about dopa to dopamine?

Back 14

Tyrosine hydroxylase, requiring BH4 cofactor (tetrahydrobiopteryn)

dopa to dopamine: requires PLP, and uses aromatic AA decarboxylase

Front 15

What about dopamine to norepi?

Norepi to epi?

Back 15

Use dopamine beta hydroxylase and vitamine C

Norepi to epi is weird. Requires SAM and phenylethanolamine methyltransferase.

Front 16

How is GABA formed?

What about histamine?

Back 16

from glutemate, using GLUTEmATE decarboxylase

Histamine comes from Histadine, via HISTADINE DECARBOXYLASE

Front 17

Where does seratonin come from?

Back 17

Seratonin comes from tryptophan, using 2 reactions: first a HYDROXYLATION and then a DECARBOXYLATION

Front 18

What do we need to know about the synthesis of heme?

Back 18

Know that it takes 8 molecules of glycine and 8 molecules of succnyl CoA.

Regulating enzyme is delta aminolevulinic acid synthase.

Acute intermitnant porferia is caused by deficiency in porpho ilinogen deaminase.