MEARA sequence repeat of human CstF-64 polyadenylation factor is helical in solution. A spectroscopic and calorimetric study

John M. Richardson, Kevin Wyatt McMahon, Clinton C. MacDonald, George I. Makhatadze

Research output: Contribution to journalArticle

Abstract

The primary structure of the human CstF-64 polyadenylation factor contains 12 nearly identical repeats of a consensus motif of five amino acid residues with the sequence MEAR(A/G). No known function has yet been ascribed to this motif; however, according to secondary structure prediction algorithms, it should form a helical structure in solution. To validate this theoretical prediction, we synthesized a 31 amino acid residue peptide (MEARA6) containing six repeats of the MEARA sequence and characterized its structure and stability by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). No effects of concentration on the CD or DSC properties of MEARA6 were observed, indicating that the peptide is monomeric in solution at concentrations up to 2 mM. The far UV-CD spectra of MEARA6 indicates that at a low temperature (1 °C) the MEARA6 peptide has a relatively high helical content (76% at pH 2.0 and 65% at pH 7.0). The effects of pH and ionic strength on the CD spectrum of MEARA6 suggest that a number of electrostatic interactions (e.g., i, i + 3 Arg/Glu ion pair, charge-dipole interactions) contribute to the stability of the helical structure in this peptide. DSC profiles show that the melting of MEARA6 helix is accompanied by positive change in the enthalpy. To determine thermodynamic parameters of helix-coil transition from DSC profiles for this peptide, we developed a new, semiempirical procedure based on the calculated function for the heat capacity of the coiled state for a broad temperature range. The application of this approach to the partial molar heat capacity function for MEARA6 provides the enthalpy change for helix formation calculated per amino acid residue as 3.5 kJ/mol.

Original languageEnglish (US)
Pages (from-to)12869-12875
Number of pages7
JournalBiochemistry®
Volume38
Issue number39
DOIs
StatePublished - Sep 28 1999
Externally publishedYes

Fingerprint

mRNA Cleavage and Polyadenylation Factors
Differential Scanning Calorimetry
Circular Dichroism
Differential scanning calorimetry
Peptides
Dichroism
Amino Acids
Specific heat
Enthalpy
Hot Temperature
Circular dichroism spectroscopy
Amino Acid Motifs
Temperature
Coulomb interactions
Ionic strength
Static Electricity
Thermodynamics
Osmolar Concentration
Freezing
Spectrum Analysis

ASJC Scopus subject areas

  • Biochemistry

Cite this

MEARA sequence repeat of human CstF-64 polyadenylation factor is helical in solution. A spectroscopic and calorimetric study. / Richardson, John M.; McMahon, Kevin Wyatt; MacDonald, Clinton C.; Makhatadze, George I.

In: Biochemistry®, Vol. 38, No. 39, 28.09.1999, p. 12869-12875.

Research output: Contribution to journalArticle

Richardson, John M. ; McMahon, Kevin Wyatt ; MacDonald, Clinton C. ; Makhatadze, George I. / MEARA sequence repeat of human CstF-64 polyadenylation factor is helical in solution. A spectroscopic and calorimetric study. In: Biochemistry®. 1999 ; Vol. 38, No. 39. pp. 12869-12875.
@article{413d1266de334344b028b822ef4e0cc8,
title = "MEARA sequence repeat of human CstF-64 polyadenylation factor is helical in solution. A spectroscopic and calorimetric study",
abstract = "The primary structure of the human CstF-64 polyadenylation factor contains 12 nearly identical repeats of a consensus motif of five amino acid residues with the sequence MEAR(A/G). No known function has yet been ascribed to this motif; however, according to secondary structure prediction algorithms, it should form a helical structure in solution. To validate this theoretical prediction, we synthesized a 31 amino acid residue peptide (MEARA6) containing six repeats of the MEARA sequence and characterized its structure and stability by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). No effects of concentration on the CD or DSC properties of MEARA6 were observed, indicating that the peptide is monomeric in solution at concentrations up to 2 mM. The far UV-CD spectra of MEARA6 indicates that at a low temperature (1 °C) the MEARA6 peptide has a relatively high helical content (76{\%} at pH 2.0 and 65{\%} at pH 7.0). The effects of pH and ionic strength on the CD spectrum of MEARA6 suggest that a number of electrostatic interactions (e.g., i, i + 3 Arg/Glu ion pair, charge-dipole interactions) contribute to the stability of the helical structure in this peptide. DSC profiles show that the melting of MEARA6 helix is accompanied by positive change in the enthalpy. To determine thermodynamic parameters of helix-coil transition from DSC profiles for this peptide, we developed a new, semiempirical procedure based on the calculated function for the heat capacity of the coiled state for a broad temperature range. The application of this approach to the partial molar heat capacity function for MEARA6 provides the enthalpy change for helix formation calculated per amino acid residue as 3.5 kJ/mol.",
author = "Richardson, {John M.} and McMahon, {Kevin Wyatt} and MacDonald, {Clinton C.} and Makhatadze, {George I.}",
year = "1999",
month = "9",
day = "28",
doi = "10.1021/bi990724r",
language = "English (US)",
volume = "38",
pages = "12869--12875",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "39",

}

TY - JOUR

T1 - MEARA sequence repeat of human CstF-64 polyadenylation factor is helical in solution. A spectroscopic and calorimetric study

AU - Richardson, John M.

AU - McMahon, Kevin Wyatt

AU - MacDonald, Clinton C.

AU - Makhatadze, George I.

PY - 1999/9/28

Y1 - 1999/9/28

N2 - The primary structure of the human CstF-64 polyadenylation factor contains 12 nearly identical repeats of a consensus motif of five amino acid residues with the sequence MEAR(A/G). No known function has yet been ascribed to this motif; however, according to secondary structure prediction algorithms, it should form a helical structure in solution. To validate this theoretical prediction, we synthesized a 31 amino acid residue peptide (MEARA6) containing six repeats of the MEARA sequence and characterized its structure and stability by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). No effects of concentration on the CD or DSC properties of MEARA6 were observed, indicating that the peptide is monomeric in solution at concentrations up to 2 mM. The far UV-CD spectra of MEARA6 indicates that at a low temperature (1 °C) the MEARA6 peptide has a relatively high helical content (76% at pH 2.0 and 65% at pH 7.0). The effects of pH and ionic strength on the CD spectrum of MEARA6 suggest that a number of electrostatic interactions (e.g., i, i + 3 Arg/Glu ion pair, charge-dipole interactions) contribute to the stability of the helical structure in this peptide. DSC profiles show that the melting of MEARA6 helix is accompanied by positive change in the enthalpy. To determine thermodynamic parameters of helix-coil transition from DSC profiles for this peptide, we developed a new, semiempirical procedure based on the calculated function for the heat capacity of the coiled state for a broad temperature range. The application of this approach to the partial molar heat capacity function for MEARA6 provides the enthalpy change for helix formation calculated per amino acid residue as 3.5 kJ/mol.

AB - The primary structure of the human CstF-64 polyadenylation factor contains 12 nearly identical repeats of a consensus motif of five amino acid residues with the sequence MEAR(A/G). No known function has yet been ascribed to this motif; however, according to secondary structure prediction algorithms, it should form a helical structure in solution. To validate this theoretical prediction, we synthesized a 31 amino acid residue peptide (MEARA6) containing six repeats of the MEARA sequence and characterized its structure and stability by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). No effects of concentration on the CD or DSC properties of MEARA6 were observed, indicating that the peptide is monomeric in solution at concentrations up to 2 mM. The far UV-CD spectra of MEARA6 indicates that at a low temperature (1 °C) the MEARA6 peptide has a relatively high helical content (76% at pH 2.0 and 65% at pH 7.0). The effects of pH and ionic strength on the CD spectrum of MEARA6 suggest that a number of electrostatic interactions (e.g., i, i + 3 Arg/Glu ion pair, charge-dipole interactions) contribute to the stability of the helical structure in this peptide. DSC profiles show that the melting of MEARA6 helix is accompanied by positive change in the enthalpy. To determine thermodynamic parameters of helix-coil transition from DSC profiles for this peptide, we developed a new, semiempirical procedure based on the calculated function for the heat capacity of the coiled state for a broad temperature range. The application of this approach to the partial molar heat capacity function for MEARA6 provides the enthalpy change for helix formation calculated per amino acid residue as 3.5 kJ/mol.

UR - http://www.scopus.com/inward/record.url?scp=0033613218&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033613218&partnerID=8YFLogxK

U2 - 10.1021/bi990724r

DO - 10.1021/bi990724r

M3 - Article

C2 - 10504257

AN - SCOPUS:0033613218

VL - 38

SP - 12869

EP - 12875

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 39

ER -