79
and poly (G) (41 U/mg). The RNase inhibited [
3
H-methyl]-thymidine uptake by
leukemia L1210 cells with an IC 50 of 60 μM (Guan et al. 2007).
A peptide with RNase activity was isolated from fruiting bodies of the mushroom Agrocybe cylindracea. Its molecular mass was 9.5 kDa and demonstrating an
N-terminal sequence similar to ubiquitin. It exhibited maximal RNase activity at
pH 6 and the activity was stable over the temperature range of 0–60 °C. It showed
antiproliferative activity on leukemia cell line (M1) and hepatoma cell line (HepG2)
and also enhanced NO production in murine peritoneal macrophages with a potency
comparable to that of lipopolysaccharide. RNase exerted activity preferentially on
poly (C), much lower activity on poly (U), and negligible activity on poly (A) and
poly (G) (Ngai et al. 2003).
A potent homodimeric ribonuclease exhibiting a molecular weight of 29 kDa
was isolated from the fresh sclerotia of the mushroom Pleurotus tuber-regium. It
showed strong ribonucleolytic activity toward poly (G), slight activity toward poly
(U) and poly (A), and minimal activity toward poly (C). Its optimal pH was 6.5
using yeast transfer RNA as substrate. RNase activity was resistant to heating at
100 °C for 30 min but was inhibited by some salts. The protein inhibited cell-free
translation in a rabbit reticulocyte lysate with an IC 50 of 0.09 nM. Three of the four
amino acid residues of the active site (positions 38–41) of the RNase of Pleurotus
ostreatus, YNNF, were also found at positions 17–20 in the RNase of Pleurotus
tuber-regium. However, unlike the RNase of Pleurotus ostreatus, no cysteine residues were detected in the N-terminal sequence (Wang and Ng 2001b).
A novel RNase has been purified from fruiting bodies of the mushroom Russula
virescens. The RNase had a molecular mass of 28 kDa. In contrast to other mushroom RNases which are monospecific, it exhibited cospecificity toward poly (A)
and poly (C). It showed an optimal pH of 4.5, which is lower than the values reported
for other mushroom RNases, and an optimal temperature of 60 °C (Wang and
Ng 2003a).
An RNase with a molecular mass of 28 kDa and specificity toward poly (U) and
poly (A) and possessing an N-terminal sequence different to previously reported
mushroom RNases was isolated from dried fruiting bodies of Dictyophora indusiata (veiled lady mushroom). It showed an RNase activity of 564 U/mg toward
yeast transfer RNA. It demonstrated an optimal pH of 4–4.5 and an optimal temperature of 60 °C and at higher temperatures activity was lost (Wang and Ng 2003b).
The N-terminal sequence of an RNase purified from fruiting bodies of the silver
plate mushroom Clitocybe maxima (family Tricholomataceae) exhibited some
homology to ribonuclease from Pleurotus ostreatus (family Pleurotaceae). However,
there is little similarity between the N-terminal sequences of RNases from various
Pleurotus species, and less resemblance between RNases from Clitocybe maxima
and Pleurotus tuber-regium. No structural relationship exists between RNases from
Clitocybe maxima and those from Volvariella volvacea, Lentinus edodes, and Irpex
lacteus. This RNase had a molecular mass of 17.5 kDa. It manifested approximately
the same ribonucleolytic potency toward poly (A) and poly (G) followed by poly
(U). Its activity toward poly (C) was comparatively very low. The optimum temperature and pH were 70 °C and 6.5–7.0, respectively (Wang and Ng 2004b).
5 Fungal Productions of Biological Active Proteins
and poly (G) (41 U/mg). The RNase inhibited [
3
H-methyl]-thymidine uptake by
leukemia L1210 cells with an IC 50 of 60 μM (Guan et al. 2007).
A peptide with RNase activity was isolated from fruiting bodies of the mushroom Agrocybe cylindracea. Its molecular mass was 9.5 kDa and demonstrating an
N-terminal sequence similar to ubiquitin. It exhibited maximal RNase activity at
pH 6 and the activity was stable over the temperature range of 0–60 °C. It showed
antiproliferative activity on leukemia cell line (M1) and hepatoma cell line (HepG2)
and also enhanced NO production in murine peritoneal macrophages with a potency
comparable to that of lipopolysaccharide. RNase exerted activity preferentially on
poly (C), much lower activity on poly (U), and negligible activity on poly (A) and
poly (G) (Ngai et al. 2003).
A potent homodimeric ribonuclease exhibiting a molecular weight of 29 kDa
was isolated from the fresh sclerotia of the mushroom Pleurotus tuber-regium. It
showed strong ribonucleolytic activity toward poly (G), slight activity toward poly
(U) and poly (A), and minimal activity toward poly (C). Its optimal pH was 6.5
using yeast transfer RNA as substrate. RNase activity was resistant to heating at
100 °C for 30 min but was inhibited by some salts. The protein inhibited cell-free
translation in a rabbit reticulocyte lysate with an IC 50 of 0.09 nM. Three of the four
amino acid residues of the active site (positions 38–41) of the RNase of Pleurotus
ostreatus, YNNF, were also found at positions 17–20 in the RNase of Pleurotus
tuber-regium. However, unlike the RNase of Pleurotus ostreatus, no cysteine residues were detected in the N-terminal sequence (Wang and Ng 2001b).
A novel RNase has been purified from fruiting bodies of the mushroom Russula
virescens. The RNase had a molecular mass of 28 kDa. In contrast to other mushroom RNases which are monospecific, it exhibited cospecificity toward poly (A)
and poly (C). It showed an optimal pH of 4.5, which is lower than the values reported
for other mushroom RNases, and an optimal temperature of 60 °C (Wang and
Ng 2003a).
An RNase with a molecular mass of 28 kDa and specificity toward poly (U) and
poly (A) and possessing an N-terminal sequence different to previously reported
mushroom RNases was isolated from dried fruiting bodies of Dictyophora indusiata (veiled lady mushroom). It showed an RNase activity of 564 U/mg toward
yeast transfer RNA. It demonstrated an optimal pH of 4–4.5 and an optimal temperature of 60 °C and at higher temperatures activity was lost (Wang and Ng 2003b).
The N-terminal sequence of an RNase purified from fruiting bodies of the silver
plate mushroom Clitocybe maxima (family Tricholomataceae) exhibited some
homology to ribonuclease from Pleurotus ostreatus (family Pleurotaceae). However,
there is little similarity between the N-terminal sequences of RNases from various
Pleurotus species, and less resemblance between RNases from Clitocybe maxima
and Pleurotus tuber-regium. No structural relationship exists between RNases from
Clitocybe maxima and those from Volvariella volvacea, Lentinus edodes, and Irpex
lacteus. This RNase had a molecular mass of 17.5 kDa. It manifested approximately
the same ribonucleolytic potency toward poly (A) and poly (G) followed by poly
(U). Its activity toward poly (C) was comparatively very low. The optimum temperature and pH were 70 °C and 6.5–7.0, respectively (Wang and Ng 2004b).
5 Fungal Productions of Biological Active Proteins