= Natalia Mast
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<Natalia Mast> is the first author of a 2011 study explaining how the <cholesterol side-chain cleavage enzyme> carries out successive reactions converting <cholesterol> toward <pregnenolone>. The investigators studied the <enzyme> bound to the first oxygenated intermediate, combining a <crystal structure> with solution measurements.<Structural basis for three-step sequential catalysis by the cholesterol side chain cleavage enzyme CYP11A1 by Natalia Mast and others>[Original byline and Abstract]{ref}
The <active site> forms an elongated cavity leading toward the <haem> group. The intermediate's placement and interactions suggested that movement within this cavity permits successive reactions while the sterol remains associated with the <enzyme>. Solution spectroscopy tested changes in its position.<Structural basis for three-step sequential catalysis by the cholesterol side chain cleavage enzyme CYP11A1 by Natalia Mast and others>[Abstract and Figure 3: structure and spectral comparisons]{ref}
The example illustrates why one catalyst can support a multistep transformation without requiring the intermediate to diffuse freely after every step. A bound structure proposes spatial constraints; measurements in solution test whether the arrangement can change, rather than assuming that a crystal captures the only functional position.
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