Wikipedia:Reference desk/Archives/Science/2019 August 28

= August 28 =

What happens when you mix sodium bicarbonate and monosaccharides in water?
A simple chemistry question: What molecules are produced in the interaction of a water-solution of sodium bicarbonate and monosaccharides? Jukeboksi (talk) 10:37, 28 August 2019 (UTC)
 * Probably nothing that interesting. Some small amount of deprotonation of the monosaccharides is possible due to the raised pH the bicarbonate causes, but I can't think of any significant chemical reactions the sodium bicarbonate would do to change the main structure of the monosacharide.  -- Jayron 32 12:26, 28 August 2019 (UTC)
 * Maybe an effect on the pyranose/furanose/open-chain equilibrium in certain cases? DMacks (talk) 13:36, 28 August 2019 (UTC)
 * Certainly stronger bases could, but even saturated sodium carbonate solution wouldn't be able to raise the pH enough to do that. -- Jayron 32 15:34, 28 August 2019 (UTC)
 * My only data point at hand is that rates of mutarotation vary substantially with even a 0.1 or 0.2 pH-unit change in the weak-acid range, occurring via the transiently-existing open-chain form. Presumably it accelerates further at weak-base pH. No idea whether there is any effect on the relative stabilities of the anomers. DMacks (talk) 17:03, 28 August 2019 (UTC)
 * Na+ (140mM), HCO3- (25mM) and monosaccharides like glucose (>4mM) float around in our plasma without reacting. Klbrain (talk) 23:20, 28 August 2019 (UTC)

Unrinsed hands
General wisdom says that remnants of soap after washing and drying one's hands without rinsing out all the soap with water can itch. What's the physical mechanism behind this itch? Is soap somehow toxic? 93.136.143.215 (talk) 12:30, 28 August 2019 (UTC)
 * I thought you were saying "urinised" hands there. For this you might get a white crust on your skin, with an article here: uremia. However to get your wanted answer it is very simple to search on Google with "itch caused by soap" and it seems to be due to dry skin. Graeme Bartlett (talk) 12:43, 28 August 2019 (UTC)


 * Whether it is drying depends on the type of "soap" used. Detergents (common in liquid "soaps") can be drying, especially if they include alcohol to kill bacteria. Some solid soaps, on the other hand, contain moisturizers, like Dove. SinisterLefty (talk) 13:38, 28 August 2019 (UTC)


 * You mean soaps with moisturizers don't typically cause itching? 93.136.2.166 (talk) 03:58, 29 August 2019 (UTC)


 * If dry skin is the cause, then moisturizers should fix that. But if there is some other cause, it won't. SinisterLefty (talk) 04:03, 29 August 2019 (UTC)

What's the highest molecular weight artificial amino acid?
Sagittarian Milky Way (talk) 18:41, 28 August 2019 (UTC)


 * I don't think that's even a meaningful question. There is probably a 'largest thing commonly referred to as an amino acid', but since the R group can be literally anything, there is no size limit. If you want to be ridiculous, an entire network of covalently bonded proteins could be described as "the side chain" of a cysteine that connects by a disulfide bridge. Someguy1221 (talk) 20:14, 28 August 2019 (UTC)


 * What is the largest thing commonly referred to as an amino acid that has been synthesized? Sagittarian Milky Way (talk) 21:13, 28 August 2019 (UTC)
 * Are you restricting to alpha? Bucky amino acids ( 10.1039/B614298B) are pretty large. DMacks (talk) 21:32, 28 August 2019 (UTC)
 * What is the heaviest with a side chain only on the alpha carbon? Would proteins made from buckyball amino acids taste more like food or more like purified charcoal? (tasteless and odorless right?) Do they have any calories? Toxicity? Do they look black? Sagittarian Milky Way (talk) 13:50, 29 August 2019 (UTC)
 * Properties like taste will depend on how soluble they are in water. An amino acid like what you desrcribe would be slightly soluble and probably have a slight taste. But for a protein made from heavy amino acids, it is probably tasteless like other proteins are. Calories for human's come about if they are metabolised. About all that could happen is that the protein is broken into individual amino acids. Those unusual amino acids would not be metabolized. Secondly with bulky side chains, the digestive enzymes would not be able to reach the bonds to break them up, and with low solubility, the protein would be indigestible. You can see hazards info for C60 here: https://pubchem.ncbi.nlm.nih.gov/compound/123591#section=Safety-and-Hazards. Although they may not be particularly hazardous according to that, our article mentions inhibition on the three isoforms of nitric oxide synthase. For colour see Buckminsterfullerene (probably brown). Graeme Bartlett (talk) 23:13, 1 September 2019 (UTC)