Kurt Wüthrich was born on this day in 1938. On his 79th birthday, in 2017, the Nobel committee gave the chemistry prize to cryo-electron microscopy. Both are answers to the same problem: how do you see a protein that won't sit still in a crystal? For most of the 20th century, seeing a protein meant crystallizing it and shooting X-rays through it. Plenty of proteins refuse to crystallize, and the ones that do are frozen in a single pose. Wüthrich went after the ones that won't, using NMR on proteins tumbling free in water. The spectrum looked like a storm of overlapping peaks, none of them labeled. He named them by walking the chain one amino acid at a time, then used the distances between neighboring hydrogens as measuring tapes to fold the chain into a shape. In the mid-1980s his group solved the first complete protein structure in solution, no crystal at all. Nobel, 2002. He also played serious competitive football. Cryo-EM came at it from another direction. Jacques Dubochet froze molecules so fast the water turned to glass instead of ice. Joachim Frank worked out how to average thousands of noisy images into one clear one. Richard Henderson spent decades pushing the microscope toward atomic resolution. Today a large share of new structures come from cryo-EM. Nobel week starts tomorrow. Whatever wins, every structure in it will still be checked against a single page G. N. Ramachandran drew in Madras in 1963. More on him Thursday. If you want to rotate some of these structures yourself, the structure lessons at Biochemistrypedia load them live from the Protein Data Bank: biochemistrypedia.com

Bob Kretsinger died this week at 89. In 1973, at UVA, he found how cells read calcium: two helices cradling a single ion. He drew it as a hand, forefinger and thumb, and named it the EF-hand. It's in every biochemistry textbook. He also sculpted, and built his own house.

Louise Johnson was born on this day in 1940. As a grad student she helped solve lysozyme, the first enzyme structure anyone had ever seen. When it ran in Nature in 1965, her paper was printed right behind it, showing where the enzyme grabs hold of its substrate. She was 24.

Friedrich Wöhler died on this day in 1882. He trained a generation of chemists at Göttingen, but history remembers him for one flask. In 1828, at 27, he heated ammonium cyanate, an ordinary lab salt, and found crystals of urea. The science of his day said urea could only come from a living kidney, because life ran on forces beyond chemistry. He knew exactly what he had. He wrote to his mentor Berzelius that he could now make urea without a kidney, whether of man or dog. One experiment didn't kill vitalism. That took decades, and the last blow came in 1897, when Eduard Buchner fermented sugar with cell-free yeast juice. But after Wöhler, the burden of proof had switched sides. Life's chemistry was chemistry. We turned that whole story, from Wöhler's flask to Buchner's juice, into an interactive opening chapter at Biochemistrypedia. It's free for anyone teaching or learning biochem: biochemistrypedia.com

Beneath a field of clover, something extraordinary is happening. Bacteria living in the plants’ root nodules take nitrogen from the air and convert it into ammonia—the first step toward making that nitrogen available for proteins, DNA, and growth. The plants provide fuel for the work. An enzyme called nitrogenase performs the chemistry at ordinary temperatures and pressures. It’s a biochemical feat that still astonishes me. Fritz Haber found another way to make ammonia from nitrogen and hydrogen. Carl Bosch and his team turned that laboratory achievement into an industry, using tremendous heat and pressure. In 1913, the first industrial Haber–Bosch ammonia plant opened at Oppau, Germany. The fertilizer made possible by that breakthrough now helps feed roughly half the world. But fixed nitrogen also supplies the raw material for many explosives. During World War I, Bosch helped Germany produce nitrates for munitions. Haber separately became a leading architect of poison-gas warfare. Their later histories resist easy summaries, too. Haber, who was Jewish, left Germany after the Nazis came to power. Bosch opposed the persecution of Jewish scientists while leading IG Farben as it developed ties to the regime. And there was Oppau. At 7:32 a.m. on September 21, 1921—105 years ago today—stored fertilizer exploded there during blasting intended to loosen the hardened material. More than 500 people died. This was an industrial disaster, distinct from the deliberate use of chemistry in war. Both belong in the history of this extraordinary achievement. I teach the Haber–Bosch process every year, and I try to teach it whole: the biology that preceded it, the ingenuity that made it possible, and the human decisions that shaped its consequences. I hear an echo in today’s conversations about AI. The technologies are very different, but the question feels familiar: how do we make the most of a powerful capability while taking seriously the harm that deliberate misuse—or failures in ordinary use—can cause? On this anniversary, I’m thinking about the people of Oppau, whose lives are also part of the story of the chemistry that feeds us.