Læknablaðið : fylgirit - 01.05.1978, Qupperneq 144

Table I •
The complete amino acid sequence of amyloid protein AA from the liver of
a patient (T.H.) with JRA.
5 10 15 20
JRA NH^-Arg-Ser-Phe-Phe-Ser-Phe-Leu-Gly-Glu-Ala-Phe-Asp-Gly-Ala-Arg-Asp-Met-Trp-Arg-Ala
25 30 35 40
JRA Tyr-Ser-Asn-Met-Arg-Glu-Ala-Asn-Tyr-Ile-Gly-Ser-Asp-Lys-Tyr-Phe-His-Ala-Arg-Gly
45 50 55 60
JRA Asn-Tyr-Asp-Ala-Ala-Lys-Arg-Gly-Pro-Gly-Gly-Val-Trp-Ala-Ala-Glu-Ala-Ile-Ser-Asp
65 70
JRA Ala-Arg-Glu-Asn-Ile-Gln-Arg-Phe-Phe-Gly-His-Gly-Ala-Glu-Asn-Ser-COOH
Eesults and discussion:
Protein AA was obtained by gel filtration (8,9)
from amyloid T.H. liver (JEA) with a yield of
41%, and from J.L. liver (AS) with a yield of
437o. The amino acid sequence analyses revealed
that protein AA (TH, liver) consisted of 76 amino
acid (16), 1 (Table I). Protein AA (J.L. liver)
consisted of only 64 amino acids (17), otherwise
the amino acid sequence was identical with that
of protein AA (TH, liver). Another protein AA
from rheumatoid arthritis reported by Ein et al.
(5,6) consisted of only 45 amino acids (molecular
weight 4,500), but the sequence of these 45 amino
acids was identical with the 45 amino-terminal
amino acids of protein AA from TH liver (JEA)
and JL-liver (AS). These results indicate that
protein AA is originated by proteolytic cleavage
at different positions of a larger precursor pro-
tein.
Practically all patients with secondary amiloi-
dosis and many patients with diseases often
complicated by amyloidosis like rheumatoid ar-
thritis have a serum protein SAA (for nomencla-
ture see 2), which is larger (molecular weight
14.000) but otherwise closely related to the
amyloid protein AA (1,10). Protein SAA may
be the precursor of protein AA, alternatively
both AA and SAA are possibly derived from a
common, larger precursor protein. Protein
SAA related material has been found in cultures
of fibroblasts (13), thus SAA (and AA) may be
a protein of connective tissue origin. No protein
AA was detected by gel filtration or immuno-
diffusion of normal tissue extracts.
The void volume (VQ) material was eluted
with a yield of 387o from amyloid T.H. liver and
2C% from amyloid J.L. liver. Practically all
the protein material was eluted in the void
volume when normal tissue extracts were gel
filtered (Fig. 2). The amino-terminal amino
acid of the V0-materials of both amyloid fibrils
and normal tissues seemed to be blocked. The
amino acid composition analyses revealed a
high degree of similarity between V0-materials
from different amyloid fibrils (of immunoglobulin
and protein AA types) and between amyloid
fibrils and the V0-material from normal organs.
A representative example is shown in table H,
142