Alanine biochemistry: from genericness to mutagenesis to glucose-alanine cycle, here's what to know

Alanine biochemistry - amino acid chirality, alanine scanning, glucose-alanine cycle, & more… Fa L-Ala L-Ala L-Ala L-Ala! There’s a lot to love about ALANINE! It’s the smallest CHIRAL amino acid ever seen (mostly in the L-form!). Alanine is kinda the “generic” amino acid. It’s not the smallest (glycine beats it) but its methyl (CH₃) comes in 2nd. It isn’t very reactive, and is isn’t “essential” in the sense that we need to get it directly from our food but it IS very important. Just ask your muscles - which rely on the glucose-alanine cycle to remove nitrogen “waste” and get fresh sugar. 
 
blog form : bit.ly/alaninec... ; longer video: TH-cam: • Alanine biochemistry -...  
 
It’s Day 2 of #20DaysOfAminoAcids - the bumbling biochemist’s version of an advent calendar. Amino acids are the building blocks of proteins. There are 20 (common) genetically-specified ones, each with a generic backbone to allow for linking up through peptide bonds to form chains (polypeptides) that fold up into functional proteins, as well as unique side chains (aka “R groups” that stick off like charms from a charm bracelet). Each day I’m going to bring you the story of one of these “charms” - what we know about it and how we know about it, where it comes from, where it goes, and outstanding questions nobody knows. 
 
More on amino acids in general here bit.ly/aminoaci...
 
But today’s the spotlight’s on Alanine (abbreviated Ala, A), which is “coded for” by the RNA codon “words” starting with GC - so GCU, GCC, GCA, & GCG. 
 
note: when we say “coded for” it basically just means spelled out the protein’s genetic instructions. The “original copy” of a protein’s instructions are written in DNA in the form of genes (stretches of chromosomes). messenger RNA (mRNA) copies of these protein “recipes” are made and handed off to protein-making complexes called ribosomes who read its code and stitch together the corresponding amino acids (which are brought by transfer RNAs (tRNAs) that have a complementary 3-letter “anticodon”).  
 
Alanine is one of 2 protein amino acids that was made from scratch (via synthesis) before it was actually shown to be a protein letter. It was first made in cells a really really really long time ago. But it was first made & purified in the lab 1850 by Adolph Strecker. He named it alanin (German), using the first syllable of the word aldehyde to denote its origin - he made it from aldehyde-ammonia, finding it by chance when he was trying to find a way to make lactic acid doi.org/10.102...  
 
As for bragging rights for isolating it from protein (and proving it), that’s a bit complicated…. In 1875 Schützenberger and Bourgeois isolated it from base hydrolysis of silk - or so they say… They didn’t do any rigorous analyzing of it but they said it seemed to be that Alanine thing Strecker had made. A few years later Schützenberger did some more thorough analysis - that original silk mix they’d found had a mix of stuff & Schützenberger further separated the stuff by fractional crystallization (different chemicals will crystallize under different conditions so if you change the conditions over and over in the right ways you can get a mixture to separate itself). Once he’d done that, he measured how much carbon, nitrogen & hydrogen the fractions had. One was consistent with alanine, but he didn’t do any other tests on it so he didn’t have proof that those atoms were hooked up the alanine way. Then in 1888, Theodor Weyl purified it from hydrolysis of silk (silk happens to be really rich in alanine). And he characterized it further and claims credit. 
 
I’m not one to care about credit - science is a team effort and every contribution helps. What I care about is what is find out. So that’s what I want to now tell you about. 
 
Alanine (Ala, A) has a methyl group (-CH₃) for its R. Atoms bond together by sharing electrons (negatively-charged subatomic particles that whizz around the atoms’ dense central nuclei where the positively-charged protons & neutral neutrons hang out). If they share fair, and there’s an equal number of protons & neutrons, the charges cancel out and the molecule is evenly charged everywhere. But if they don’t share fairly, the more electronegative (electron-hogging) atoms will pull electron density away from the less electronegative atoms, shifting the electron cloud and disrupting the even charge balance leading to a charge imbalance we call POLARITY. 
 
Finished in comments