Observation of two types of charge-density-wave orders in superconducting La2-xSrxCuO4.

The discovery of charge- and spin-density-wave (CDW/SDW) orders in superconducting cuprates has altered our perspective on the nature of high-temperature superconductivity (SC). However, it has proven difficult to fully elucidate the relationship between the density wave orders and SC. Here, using resonant soft X-ray scattering, we study the archetypal cuprate La2-xSrxCuO4 (LSCO) over a broad doping range. We reveal the existence of two types of CDW orders in LSCO, namely CDW stripe order and CDW short-range order (SRO). While the CDW-SRO is suppressed by SC, it is partially transformed into the CDW stripe order with developing SDW stripe order near the superconducting Tc. These findings indicate that the stripe orders and SC are inhomogeneously distributed in the superconducting CuO2 planes of LSCO. This further suggests a new perspective on the putative pair-density-wave order that coexists with SC, SDW, and CDW orders.

Secretion of tetrain, a Tetrahymena cysteine protease, as a mature enzyme and its identification as a member of the cathepsin L subfamily.

A protease in the culture medium of Tetrahymena pyriformis was purified to homogeneity. The purified protease had an apparent molecular mass of 28 kDa on SDS/PAGE. The amino acid sequences of the N-terminal and internal peptides of the protease showed complete identity with those of tetrain, an enzyme previously reported as a Tetrahymena cysteine protease but not characterized in detail. Two overlapping cDNA clones for tetrain were sequenced, and the nucleotide sequence predicts that these clones encode a 330-amino acid protein composed of a 16-residue N-terminal signal sequence followed by a 103-residue propeptide and a 211-residue mature protease. The primary structure and enzymatic properties support the conclusion that tetrain belongs to the cathepsin L subfamily. Immunoblotting analyses showed that mature tetrain was found exclusively in the culture medium. Immunofluorescence microscopy demonstrated that tetrain was concentrated in or around the food vacuoles of cells in the late logarithmic phase, but the staining of food vacuoles was not obvious in the stationary phase. These results suggest that tetrain is synthesized at the logarithmic phase and is secreted into the culture medium as a mature form.

Release of a newly-identified cysteine protease, tetrain, from Tetrahymena into culture medium during the cell growth.

Protease activity in the culture medium of Tetrahymena pyriformis markedly increased during the growth of the ciliate. The protease activity in the culture medium was purified by sequential column chromatographies. The purified protease had an apparent molecular mass of 28 kDa. N-terminal amino acid sequencing analysis suggested that the protease is a mature form of cysteine protease. Requirements of free sulfhydryl groups for activity and sensitivity to N-tosyl-L-phenylalanine chloromethyl ketone and Na-p-tosyl-L-lysine chloromethyl ketone also indicated that the protease is a member of the papain family of cysteine proteases. The protease was designated as tetrain. Immunoblotting analyses showed that tetrain was present in higher amount in the culture medium in the stationary phase than in the logarithmic phase. Tetrain has high activities at neutral to alkaline pH values. This suggests that tetrain has functional roles in the culture medium in the stationary phase, because the pH of the culture medium became alkaline with the progress of Tetrahymena growth.