Contribution of electrostatics to the binding of pancreatic-type ribonucleases to membranes

Biochemistry. 2013 Sep 17;52(37):6304-12. doi: 10.1021/bi400619m. Epub 2013 Aug 30.

Abstract

Pancreatic-type ribonucleases show clinical promise as chemotherapeutic agents but are limited in efficacy by the inefficiency of their uptake by human cells. Cellular uptake can be increased by the addition of positive charges to the surface of ribonucleases, either by site-directed mutagenesis or by chemical modification. This observation has led to the hypothesis that ribonuclease uptake by cells depends on electrostatics. Here, we use a combination of experimental and computational methods to ascertain the contribution of electrostatics to the cellular uptake of ribonucleases. We focus on three homologous ribonucleases: Onconase (frog), ribonuclease A (cow), and ribonuclease 1 (human). Our results support the hypothesis that electrostatics are necessary for the cellular uptake of Onconase. In contrast, specific interactions with cell-surface components likely contribute more to the cellular uptake of ribonuclease A and ribonuclease 1 than do electrostatics. These findings provide insight for the design of new cytotoxic ribonucleases.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Boron Compounds / chemistry
  • Cattle
  • Computational Biology
  • Computer Simulation
  • Endocytosis / physiology
  • Fluorescent Dyes
  • Humans
  • Models, Molecular
  • Phosphatidylserines / chemistry
  • Ribonuclease, Pancreatic / chemistry
  • Ribonuclease, Pancreatic / metabolism*
  • Ribonucleases / chemistry
  • Ribonucleases / metabolism
  • Static Electricity
  • Unilamellar Liposomes / chemistry
  • Unilamellar Liposomes / metabolism*

Substances

  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Boron Compounds
  • Fluorescent Dyes
  • Phosphatidylserines
  • Unilamellar Liposomes
  • Ribonucleases
  • Ribonuclease, Pancreatic
  • ranpirnase