GLOSSARY

Mitochondrial Enzyme is associated with mitochondrial compartments.

Location determines access to substrates, cofactors and local conditions. Cytosol, mitochondrial matrix, peroxisomes and nucleus are not equivalent environments. Microsomal usually refers to a laboratory membrane fraction largely derived from endoplasmic reticulum, not a normal independent organelle in living cells. Direct transfer of intermediates between enzymes requires evidence; proximity or membership of the same compartment alone does not establish substrate channeling or its magnitude.

An enzyme may be soluble, membrane-bound or part of a complex. Multienzyme organization can facilitate intermediate transfer, but proximity alone does not prove direct substrate channeling. A multifunctional enzyme performs several reaction types, whereas a complex may contain separate proteins. Understanding actual capacity requires component abundance, cellular location and substrate access to be considered alongside measured function rather than inferring activity from organization alone.

Cells and organs do not share one uniform pool; cytosol, mitochondria and blood have different roles. Membranes and carriers determine direct passage versus shuttle requirements. Blood measurements do not fully reveal conditions inside muscle. Compartmentation prevents interpreting one sample or supplement as a guaranteed energy change in every cell. Distinguish local processes from whole-body averages rather than assuming a circulating level represents all intracellular reactions.