Editing Catalase (section)

== Structure ==
Human catalase forms a [[tetramer]] composed of four [[Protein subunit|subunits]], each of which can be conceptually divided into four domains.<ref name = "Putnam_2000" >{{cite journal | vauthors = Putnam CD, Arvai AS, Bourne Y, Tainer JA | title = Active and inhibited human catalase structures: ligand and NADPH binding and catalytic mechanism | journal = Journal of Molecular Biology | volume = 296 | issue = 1 | pages = 295–309 | date = February 2000 | pmid = 10656833 | doi = 10.1006/jmbi.1999.3458 }}</ref> The extensive core of each subunit is generated by an eight-stranded antiparallel [[Beta barrel|β-barrel]] (β1-8), with nearest neighbor connectivity capped by β-barrel loops on one side and α9 loops on the other.<ref name = "Putnam_2000"  /> A [[Alpha helix|helical]] domain at one face of the β-barrel is composed of four C-terminal helices (α16, α17, α18, and α19) and four helices derived from residues between β4 and β5 (α4, α5, α6, and α7).<ref name = "Putnam_2000"  /> Alternative splicing may result in different protein variants.