A cytosolic isocitrate-dehydrogenase isoform. Certain cancer-associated variants acquire an altered catalytic activity producing 2-hydroxyglutarate.^[ref]

An extraembryonic endodermal epithelium associated with early mammalian development. It supplies signals and matrix and must be distinguished from definitive endoderm formed through gastrulation.

A hydrosilylation cycle involving Si–H oxidative addition, alkene insertion into the metal–hydride bond, and C–Si reductive elimination. This defines the conventional version; insertion into a metal–silyl bond describes a modified alternative.

ATP hydrolysis converts ATP with water to products commonly including ADP and inorganic phosphate. Its available Gibbs free energy depends on chemical conditions and can drive a coupled process; ATP binding and hydrolysis can have distinct structural roles.

GTP hydrolysis converts GTP with water to GDP and inorganic phosphate. In many signaling G proteins, it favors a switch toward an inactive effector-binding state.

Conversion of an acetal and water to its corresponding carbonyl compound and alcohols.

Cleavage of an ester using water, yielding a carboxylic acid or carboxylate and an alcohol, depending on conditions.

Hydrolytic deamination replaces an amino group using water, releasing Ammonia or ammonium according to pH. Adenosine deaminase introduces solvent oxygen at the C6 position of adenosine.

Aqueous hydrogen iodide is strongly acidic, and iodide can also participate in reductive transformations. These roles must be separated when explaining a reaction.

The gaseous hydrogen halide consisting of one hydrogen atom and one bromine atom. Its molecular vibration can be studied through its vibrational fundamental and weak vibrational overtones. The aqueous acid and the isolated diatomic molecule should be distinguished when specifying a dissociation process.^[ref]

The diatomic molecule containing one hydrogen atom and one iodine atom. Its measured spectroscopic wavenumbers include anharmonic corrections beyond the two-term Morse oscillator model.^[ref]

A functional group interaction profile maps the free-energy contribution of a solute donor–acceptor contact after accounting for competing solvent contacts. Solvent polarity and preferential solvation determine favourable and unfavourable regions.

Formation of hydrogen bonds, either within a molecule or between interacting molecules.

Hydrogen-bond complementarity matches donor and acceptor positions in a binding interface. Two strong sites need not cooperate if their spacing or direction is incompatible; preorganization can favor a multiply hydrogen-bonded complex.

Two water molecules associated by a donor O–H···O hydrogen bond. Gas-phase pair energy does not include the complete solvent and entropy changes governing association in solution.

A cyclic pair of carboxylic acids linked by two reciprocal O–H···O=C hydrogen bonds.

An aminopyridine hydrogen-bonded dimer is a pair of aminopyridine molecules joined by complementary amino-group donors and pyridine-nitrogen acceptors. In a suitable self-complementary arrangement, each molecule supplies both a donor and an acceptor.

Two reciprocal hydrogen bonds can stabilize the pair, but solvent competition and concentration affect its abundance. A drawn dimer establishes a possible contact pattern; it does not by itself establish a quantitative association constant.

In a fixed attractive Coulomb potential, neglecting electron-electron interactions leaves hydrogenic one-particle levels with spin-inclusive degeneracy $2n^2$. The Pauli exclusion principle fills these levels in increasing energy. A partially filled degenerate shell gives many states at the same total energy; the first higher energy requires promotion to a different principal shell. This model does not describe the screening and configuration-dependent energies of a real many-electron atom.

With Bohr radius $a$, define $A_l=a[i{p}_r/\hslash -(l+1)/r+1/((l+1)a)]/\sqrt{2}$. For regular radial bound states the radial inner product and compatible domains give the displayed factorization. Expanding the first-order factors produces the centrifugal term $l(l+1){\hslash }^2/(2m{r}^2)$ and Coulomb term $-{\hslash }^2/(mar)$. factorization converts a second-order spectral problem into a positivity bound and first-order terminating-state equation.

Oxygen-directed anti addition of aluminium and hydrogen across an alkyne, giving a stereodefined vinylaluminium species.