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Oops, I forgot how to count; methionine cyclization would give a 5-membered ring with an acylsulfonium ion rather than a thiolactone

A lot of strain and because of that it’s much harder to form (because it just unwraps). Because of that, cysteine doesn’t just Leroy Jenkins all over our cells finding random proteins to mess up. But homocysteine can.

A 5-membered ring with a functional group called a thiolactone, which is very reactive. But if cysteine tries to do this, it makes a 4-membered ring. The bonds between the atoms of the ring prefer to be about 109 degrees, and a 4-membered ring has 90 degree angles, which means it’s under…

Cysteine is used all the time in our proteins and I have literally never so much as heard of a case of cysteine toxicity and homocysteine is almost identical except it’s got an extra methylene group. It turns out that makes all the difference because homocysteine can wrap around itself and form…

Accelerated heart disease, skeletal abnormalities, intellectual disability, etc. and it shares a lot of features with Marfan syndrome (a disease of connective tissue where the biggest risk is devastating cardiovascular events such as aortic dissections). I thought this was weird because…

Basically some people have a genetic condition that causes a buildup of a metabolite called homocysteine, which is very similar to an amino acid we use all the time called cysteine. In this condition, people can have issues with their connective tissues, a heightened tendency to form blood clots…

Oh and as for homocystinuria—the thiolactone is probably reacting with hydroxylysines and interfering with crosslinking of ECM proteins, hence the similarities with Marfan's.

can form via methionyl-tRNA synthetase charging errors. www.jpp.krakow.pl/journal/arch...

without catalysts) like lysine. Presumably, this isn't a problem for cysteine or methionine because they would form a β-thiolactone, and the ring strain involved there considerably raises the activation energy (but apparently it can form via cysteinyl-tRNA synthetase). Homocysteine thiolactone...

A fun fact in case you have ever wondered about this like me: high homocysteine is bad (in part) because it can cyclize into homocysteine thiolactone (a γ-thiolactone), which is highly reactive and readily forms adducts with suitable nucleophiles especially amines (amides are hard to hydrolyze...

The first volunteer has been dosed with the world's first BDBV vaccine. www.ox.ac.uk/news/2026-07...

You know what's really useful in these conversations? Data. www.kff.org/public-opini...

Not to just jump on the bandwagon of dunking on AI but... today Open Evidence told me that IgM+ plasma cells don't display surface immunoglobulin and thus surface IgM cannot used for targeting them. This is untrue. I get that it is not feasible to verify everything, but if it matters, try.

From 2003 to 2024, the number of children 17-years and under killed by US law enforcement each year increased from 8 per year (0.01 per 100 000 person-years) to 37 per year (0.05 per 100 000 person-years), noticeably outpacing the significant increases in all annual deaths caused by law enforcement.

Thanks! You too

Why are lysosomal storage diseases?

@biorxivpreprint.bsky.social Weight loss increases adipose dendritic cells, non-classical antigen presenting proteins, and cytotoxic effector cells @heathercaslin.bsky.social www.biorxiv.org/content/10.6... @uhouston.bsky.social

When purine-nucleotide levels are low, PPAT remains active, enabling cells to produce more nucleotides. But when these levels rise, the nucleotides themselves drive assembly of the PPAT–NUDT5 complex, inhibiting PPAT and shutting down further production.'

Ah. Never understood why it was only PO

Why the cefdinir hate?