Linked Life Data

9247924

Source:http://linkedlifedata.com/resource/pubmed/id/9247924

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-10-6
pubmed:abstractText
Intraerythrocytic malaria parasites avidly consume hemoglobin as a source of amino acids for incorporation into parasite proteins. An acidic organelle, the digestive vacuole, is the site of hemoglobin proteolysis. Early events in hemoglobin catabolism have been well studied. Two aspartic proteases, plasmepsins I and II, and a cysteine protease, falcipain, cleave hemoglobin into peptides. While it has been presumed that hemoglobin peptide fragments are degraded to individual amino acids by exopeptidase activity in the digestive vacuole, this hypothesis lacks experimental support. Incubation of human hemoglobin with P. falciparum digestive vacuole lysate generated a series of discrete peptide fragments with cleavage sites an average of 8.4 amino acids apart. No free amino acids could be detected and there was no evidence of peptide heterogeneity due to exopeptidase trimming. These sites correspond to points of cleavage previously established for plasmepsin I, plasmepsin II, and falcipain as well as some novel sites that suggest the existence of an additional endoproteinase. By colorimetric assay, P. falciparum has abundant aminopeptidase activity but this activity is not found in the digestive vacuoles and the parasite lacks detectable carboxypeptidase activity altogether. These data support a model for hemoglobin catabolism wherein small peptides are formed from cleavage of hemoglobin by the enzymes of the digestive vacuole and then are transported through the membrane of the digestive vacuole to the cytoplasm. There, exopeptidase activity converts the peptides to individual amino acids for parasite growth and maturation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0166-6851
pubmed:author
pubmed:issnType
Print
pubmed:volume
87
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
123-35
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Generation of hemoglobin peptides in the acidic digestive vacuole of Plasmodium falciparum implicates peptide transport in amino acid production.
pubmed:affiliation
Howard Hughes Medical Institute, Washington University, St. Louis, MO, USA.
pubmed:publicationType
Journal Article, In Vitro