What question did this study set out to answer?

To confirm the identity of the catalytic triad in lipoprotein lipase and evaluate the functional role of the surface loop that shields its active site.

August 1, 1992Biochemistry

Functional topology of a surface loop shielding the catalytic center in lipoprotein lipase

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Population

In vitro expressed wild-type and mutant lipoprotein lipases (LPL)

Comparison

Site-directed mutagenesis of putative catalytic… vs Wild-type LPL and mutant LPLs with substitutions…

Design

Preclinical

Authors

FFFabrizia FaustinellaBaylor College of Medicine LSLouis C. SmithUniversity of California, San Francisco LCLawrence ChanHong Kong Polytechnic University

Discussion

Member takes

Implication

No clinical implications for LPL deficiencies yet; extends structural insights into the catalytic triad and shielding loop for future research.

Key Points

To confirm the identity of the catalytic triad in lipoprotein lipase and evaluate the functional role of the surface loop that shields its active site.
Generated 15 single amino acid substitutions across candidate catalytic triad residues Asp156, His241, and Ser132, alongside control mutants, and expressed them in vitro.
Constructed chimeric enzymes by partially or completely replacing the 22-amino-acid surface loop (residues 217–238) with corresponding sequences from hepatic lipase or pancreatic lipase.
Assayed lipolytic enzymatic activity across all recombinant wild-type and mutant proteins.
All 15 point mutations at residues Asp156, His241, and Ser132 caused complete loss of enzymatic activity, confirming them as the functional catalytic triad.
Partial replacement (6 of 22 residues) of the surface loop with the hepatic lipase sequence preserved full activity, whereas complete replacement retained approximately 60% activity.
Complete substitution of the surface loop with the homologous pancreatic lipase loop abolished all lipase activity.

Structured PICO

Population

In vitro expressed wild-type and mutant lipoprotein lipases (LPL)

Intervention

Site-directed mutagenesis of putative catalytic triad residues (Asp156, His241, Ser132) and replacement of the shielding surface loop

Comparator

Wild-type LPL and mutant LPLs with substitutions in other positions

Outcome

Enzyme activitysurrogate

In vitro mutagenesis confirms that Asp156-His241-Ser132 constitutes the catalytic triad of lipoprotein lipase and highlights the functional flexibility of its shielding surface loop.

Cite This Study

Faustinella et al. (1992) studied this question.

synapsesocial.com/papers/6a70d1973ce530166bc2ee93 https://doi.org/10.1021/bi00147a002

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Implication

No clinical implications for LPL deficiencies yet; extends structural insights into the catalytic triad and shielding loop for future research.

Functional topology of a surface loop shielding the catalytic center in lipoprotein lipase

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Functional topology of a surface loop shielding the catalytic center in lipoprotein lipase

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider