Estudos cinéticos da catálise da reação de fenton por 3,5-di-terc-butil-catecol

Silva, Volnir de Oliveira

doi:10.11606/t.46.2010.tde-05022013-140557

Cited by 1 publication

(4 citation statements)

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“…L. donovani enters phagocytes via the macrophage CR3/mannose-fucose receptor (Blackwell et al, 1985). Interestingly, L.major metacyclics do not activate the complement cascade via the alternative pathway which is activated by non-virulent logarithmic phase promastigotes (da Silva et al, 1989). The reasons for this difference are still unclear.…”

Section: Discussionmentioning

confidence: 98%

“…Most species of Leishmania promastigotes activate the alternative pathway complement (Mosser et al, 1986;Puentes et al, 1989). In the case of L.major, C3b is fixed to the parasite surface via lipophosphoglycan, a major parasite glycolipid (Fuentes et al, 1988;Sacks, 1989). However, despite the presence of intact C3b and C5-7 complexes on the metacyclics, assembly of the CSb-9 complexes is blocked (Puentes et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…These changes can be mimicked in vitro using logarithmic and metacyclic stationary phase parasites (Sacks, 1989). In Leishmania major, changes in two surface antigens, the promastigote surface protease (also known as gp63) and the lipophosphoglycan, both involved in invasion have been noted during this transformation (Kweider et al, 1987;Sacks et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…However, Leishmania, like other virulent pathogens, have developed mechanisms to avoid killing by complement (Joiner, 1988;Fuhrman and Joiner, 1989). The infective metacylic forms of L. major only invade human macrophages in the presence of serum, but are not lysed even though 80% of the C3 on their surface is present as C3b (da Silva et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

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Leishmanial protein kinases phosphorylate components of the complement system.

et al. 1991

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Externally oriented protein kinases are present on the plasma membrane of the human parasite, Leishmania. Since activation of complement plays an important role in the survival of these parasites, we examined the ability of protein kinases from Leishmania major to phosphorylate components of the human complement system. The leishmanial protein kinase‐1 (LPK‐1) isolated from promastigotes of L. major was able to phosphorylate purified human C3, C5 and C9. Only the alpha‐chain of C3 and C5 was phosphorylated. The beta‐chain appeared not to be a substrate for this enzyme. C3b which is formed by proteolytic cleavage of C3 was not phosphorylated by LPK‐1. Trypsin treatment of phosphorylated C3 (P‐C3) resulted in the disappearance of 32P from the alpha‐chain. This was correlated with the conversion of the C3 alpha‐chain to the alpha′‐chain of C3b, and the appearance of a 9 kDa 32P fragment comigrating with the C3a fragment of C3. P‐C3 was more resistant to cleavage by trypsin than nonphosphorylated C3. LPK‐1 phosphorylated purified C3a and two synthetic peptides, C3a21R and YA‐C3a10R, derived from its COOH‐terminal end, which contain the C3a binding site to leukocytes and platelets. LPK‐1 did not phosphorylate C3a8R. Phosphoamino acid analysis of the synthetic peptides indicated that serine 71 of C3a was phosphorylated by LPK‐1. Treatment of C3 with either methylamine or freeze‐thaw C3 (H2O) prevented phosphorylation by the LPK‐1 suggesting that substrate conformation may be involved in recognition by the leishmanial enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%