Chemistry Reference
In-Depth Information
defensin molecule, which may protect sperm against microbes encountered during
their journey to an ovum.
Although a detailed description of the sugar specifi city of
- defensins
cannot be provided at this time, it clearly conforms more to the 'Hello sailor, new
in town?' model than to a highly selective one. Since these defensins must be able
to interact with a myriad of different pathogens, their ability to recognize multiple
different pathogen-associated molecular patterns is advantageous. Highly refi ned
information on the sugar specifi city of lectins larger than defensins will be pre-
sented in the next chapter.
α
- and
θ
26.12
Conclusions
Defensins are host defense peptides that have been around, in one form or
another, for over a billion years. This chapter deals with
θ
- defensins, cyclic octa-
decapeptides whose antiparallel
β
- sheets are cross -connected by a tridisulfi de
ladder.
-Defensins, which are expressed only by nonhuman primates, have anti-
microbial, antitoxic and antiviral properties. Being among the smallest currently
known lectins (please see also Chapter 19 on hevein - like domains) [12, 13] allowed
θ
θ
-defensins to be included in this textbook. Their small size and simple structure
suggests that these miniature lectins could also serve as molecular templates for
developing novel therapeutic and prophylactic agents.
Summary Box
The
- defensins - until recently, the smallest known lectins - are cyclic octa-
decapeptides expressed by the leukocytes of non-human primates. Ancestral
hominid
θ
-defensins known as RCs can protect human cells from infection by
HIV-1 and IAV viruses, acting via different mechanisms that directly or indi-
rectly use their carbohydrate-binding properties. Their small size and unique
structural characteristics make
θ
-defensins intriguing templates for designing
novel antimicrobial, antiviral and antitoxic agents.
θ
References
1
Tang YQ
et al.
A cyclic antimicrobial pep-
tide produced in primate leukocytes by the
ligation of two truncated
by T - and M - tropic strains of HIV - 1 .
Proc
Natl Acad Sci USA
2002 ; 99 : 1813 - 8 .
Roseman S . Refl ections on glycobiology.
J Biol Chem
2001 ; 276 : 41527 - 42 .
Wang W
et al.
Retrocyclin, an antiretroviral
4
α
- defensins .
Science
1999 ; 286 : 498 - 502 .
Nguyen TX
et al.
Evolution of primate
2
5
θ
-defensins: a serpentine path to a sweet
tooth .
Peptides
2003 ; 24 : 1647 - 54 .
Cole AM
et al.
Retrocyclin: a primate
peptide that protects cells from infection
θ
- defensin, is a lectin .
J Immunol
2003 ; 170 :
4708 - 16 .
Leikina E
et al.
Carbohydrate - binding mole-
cules inhibit viral fusion and entry by cross-
3
6
