Article

Rapid optimization of a peptide inhibitor of malaria parasite invasion by comprehensive N-methyl scanning.

Department of Biochemistry, La Trobe University, Victoria 3086, Australia.
Journal of Biological Chemistry (impact factor: 4.77). 02/2009; 284(14):9361-71. DOI:10.1074/jbc.M808762200 pp.9361-71
Source: PubMed

ABSTRACT Apical membrane antigen 1 (AMA1) of the malaria parasite Plasmodium falciparum has been implicated in the invasion of host erythrocytes and is an important vaccine candidate. We have previously described a 20-residue peptide, R1, that binds to AMA1 and subsequently blocks parasite invasion. Because this peptide appears to target a site critical for AMA1 function, it represents an important lead compound for anti-malarial drug development. However, the effectiveness of this peptide inhibitor was limited to a subset of parasite isolates, indicating a requirement for broader strain specificity. Furthermore, a barrier to the utility of any peptide as a potential therapeutic is its susceptibility to rapid proteolytic degradation. In this study, we sought to improve the proteolytic stability and AMA1 binding properties of the R1 peptide by systematic methylation of backbone amides (N-methylation). The inclusion of a single N-methyl group in the R1 peptide backbone dramatically increased AMA1 affinity, bioactivity, and proteolytic stability without introducing global structural alterations. In addition, N-methylation of multiple R1 residues further improved these properties. Therefore, we have shown that modifications to a biologically active peptide can dramatically enhance activity. This approach could be applied to many lead peptides or peptide therapeutics to simultaneously optimize a number of parameters.

0 0
 · 
0 Bookmarks
 · 
28 Views
  • Article: Effect of Cilazapril on Ventricular Remodeling Assessed by Doppler-Echocardiographic Assessment and Cardiac Gene Expression
    Minoru Yoshiyama, Kazuhide Takeuchi, Akihisa Hanatani, Takehiro Shimada, Yasuhiko Takemoto, Naruhito Shimizu, Takashi Omura, Shokei Kim, Hiroshi Iwao, Junichi Yoshikawa
    [show abstract] [hide abstract]
    ABSTRACT: The purpose of this study is to determine whether the administration of the ACE inhibitor cilazapril can lessen the adverse effects of ventricular remodeling, including systolic and diastolic dysfunction, modulation of fetal gene expression, increase of collagen genes, and depression of the sarcoplasmic reticulum (SR) Ca2+ ATPase gene in a myocardial infarcted (MI) rat model. At 1 day after MI, the animals were randomly assigned to cilazapril treatment or no treatment. We performed Doppler-echocardiographic examinations and measured cardiac mRNA in rats at 1 month and 3 months after MI (each group n = 8). The weights of the right (RV) and left ventricles (LV) in 1- and 3-month MI rats were significantly larger than those of the control rats. Cilazapril significantly prevented the increase. The MI rats showed systolic dysfunction, as evidenced by decreased fractional shortening (control, 34 3% vs. MI, 17 3%; P s method (control, 61 2% vs. MI, 36 3%; P < 0.01)="" in="" rats="" at="" 1="" month="" after="" operation.="" mi="" rats="" showed="" diastolic="" dysfunction,="" defined="" as="" increased="" peak="" early="" filling="" velocity,="" increased="" deceleration="" rate="" of="" the="" early="" filling="" wave,="" decreased="" late="" filling="" velocity,="" and="" an="" increase="" in="" the="" ratio="" of="" early="" filling="" to="" late="" filling="" velocity.="" cilazapril="" significantly="" prevented="" systolic="" and="" diastolic="" dysfunction="" in="" rats="" after="" mi.="" the="" increases="" in="">-MHC, -skeletal actin, ANP, and collagen I and III mRNAs in the nonischemic LV and RV were significantly suppressed by treatment with cilazapril. Depressed SR Ca2+-ATPase mRNA (nonischemic LV, 0.7-fold, P < 0.05="" vs.="" control;="" rv,="" 0.5-fold,="" p="">< 0.05="" vs.="" control)="" at="" 3="" months="" after="" mi="" was="" significantly="" restored="" to="" normal="" levels="" by="" cilazapril.="" cilazapril="" improved="" the="" adverse="" remodeling="" process="" by="" attenuating="" the="" progression="" of="" systolic="" and="" diastolic="" dysfunction,="" and="" prevented="" abnormal="" cardiac="" gene="" expression="" following="">
    Cardiovascular Drugs and Therapy 02/1998; 12(1):57-70. · 3.13 Impact Factor
  • Article: In vitro studies with recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1): production and activity of an AMA1 vaccine and generation of a multiallelic response.
    Michael C Kennedy, Jin Wang, Yanling Zhang, Aaron P Miles, Farideh Chitsaz, Allan Saul, Carole A Long, Louis H Miller, Anthony W Stowers
    [show abstract] [hide abstract]
    ABSTRACT: Apical membrane antigen 1 (AMA1) is regarded as a leading malaria blood-stage vaccine candidate. While the overall structure of AMA1 is conserved in Plasmodium spp., numerous AMA1 allelic variants of P. falciparum have been described. The effect of AMA1 allelic diversity on the ability of a recombinant AMA1 vaccine to protect against human infection by different P. falciparum strains is unknown. We characterize two allelic forms of AMA1 that were both produced in Pichia pastoris at a sufficient economy of scale to be usable for clinical vaccine studies. Both proteins were used to immunize rabbits, singly and in combination, in order to evaluate their immunogenicity and the ability of elicited antibodies to block the growth of different P. falciparum clones. Both antigens, when used alone, elicited high homologous anti-AMA1 titers, with reduced strain cross-reactivity. Similarly, sera from rabbits immunized with a single antigen were capable of blocking the growth of homologous parasite strains at levels theoretically sufficient to clear parasite infections. However, heterologous inhibition was significantly reduced, providing experimental evidence that AMA1 allelic diversity is a result of immune pressure. Encouragingly, rabbits immunized with a combination of both antigens exhibited titers and levels of parasite inhibition as good as those of the single-antigen-immunized rabbits for each of the homologous parasite lines, and consequently exhibited a broadening of allelic diversity coverage.
    Infection and Immunity 01/2003; 70(12):6948-60. · 4.16 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

20-residue peptide
 
AMA1 affinity
 
AMA1 binding properties
 
AMA1 function
 
anti-malarial drug development
 
biologically active peptide
 
blocks parasite invasion
 
broader strain specificity
 
global structural alterations
 
lead peptides
 
malaria parasite Plasmodium falciparum
 
N-methylation
 
parasite
 
peptide therapeutics
 
potential therapeutic
 
R1 peptide
 
R1 peptide backbone
 
rapid proteolytic degradation
 
single N-methyl group
 
systematic methylation