Figure 1–7. “PRION” supplement to the Central dogma in biology (After Kordyum, 1990).
The “mad cow disease” has proved to be a condition of this kind and has been
registered for the first time in 1985. The fears arisen from its wide spreading in the
world and the link between it and its human equivalent — the Creutzfeldt—
Jakob’s syndrome first described in 1920, made the EU (European Union) introduce
on March 25th 1996 a ban on the imports of meat and later on meat products from
such animals used as supplement toanimal feed.
What is essential in the case of prions i.e. the infectious proteins is that
they self-reproduce in a manner — distinct from the normal pathway encoded
by DNA or RNA, which is unknown for the present. Judging from the
descriptions in the literature on the etiology of the diseases caused by them
— their rapid accumulation in the brain of the diseased animals as long
strands, their resistance to UV-irradiations and proteinases, the failure to
induce an immune response and in some cases lack of antibody
production, their highly lethal impact (up to 100 %) as well as the non-mandatory
presence of the prion itself or its gene for initiation of synthesis,
it can be conjectured that these are “remains” from the primeval (ancient)
long-stranded proteins that are implicated in the studies of Ivanov (1978 a—c).
Most probably the discussions on this key problem will go on since it has
bearing on the mechanisms involved in the pre-cell evolution. In a review
article Weissmann (1991), after acknowledging the availability of convincing
proofs that the transmitter of the encephalopathies, scrapie including is a
modified normal prion in the host devoid of nucleic acids of any kind,
undertakes an attempt to reconcile the supporters of the purely protein nature
of prions and the ones looking for obligatorily participating nucleic acid as a
cause for their self-reproduction. He has forwarded a model of his own in
which the two extreme hypothesis are combined — “pure protein” and a
“nucleoprotein”.
In his book De Duve (1991) “Blueprint of a Cell: The Nature and Origin
of Life” has launched the idea that chemical evolution has led to the
creation of a protometabolism, catalyzed by oligopeptides formed prior to
the emergence of the replication and translation mechanisms. This idea of
his was subjected to severe criticism by Cavalier-Smith (1991).
The expressed opinion that primeval replication mechanisms have
existed in polypeptides (see again Dose, 1974; Fox, Dose, 1977; Dyson,
1982; Kauffmann, 1986) has encountered serious objections from a number