Subtilisin-like serine proteases (SBTs) are extracellular proteases that depend on their propeptides for zymogen maturation and activation. The function of propeptides in plant SBTs is poorly understood and was analyzed here for the propeptide of tomato subtilase 3 (SBT3PP). SBT3PP was found to be required as an intramolecular chaperone for zymogen maturation and secretion of SBT3 in vivo. Secretion was impaired in a propeptide-deletion mutant but could be restored by co-expression of the propeptide in trans. SBT3 was inhibited by SBT3PP with a K d of 74 nM for the enzyme-inhibitor complex. With a melting point of 87°C, thermal stability of the complex was substantially increased as compared with the free protease suggesting that propeptide binding stabilizes the structure of SBT3. Even closely related propeptides from other plant SBTs could not substitute for SBT3PP as a folding assistant or autoinhibitor, revealing high specificity for the SBT3-SBT3PP interaction. Separation of the chaperone and inhibitor functions of SBT3PP in a domain-swap experiment indicated that they are mediated by different regions of the propeptide and, hence, different modes of interaction with SBT3. Release of active SBT3 from the autoinhibited complex relied on a pH-dependent cleavage of the propeptide at Asn-38 and Asp-54. The remarkable stability of the autoinhibited complex and pH dependence of the secondary cleavage provide means for stringent control of SBT3 activity, to ensure that the active enzyme is not released before it reaches the acidic environment of the trans-Golgi network or its final destination in the cell wall. Subtilases (SBTs)2 are found in all kingdoms of life. They constitute the S8 family of serine peptidases (1) and are characterized by a specific arrangement of the aspartate, histidine, and serine residues of the catalytic triad within the active site of the enzyme (2). SBTs include general proteases with relaxed substrate specificity for protein degradation and turnover as well as processing enzymes that cleave selected substrates at highly specific sites (3). Most bacterial SBTs are of the catabolic type including subtilisin E and subtilisin Carlsberg from Bacillus subtilis and Bacillus licheniformis, the prototypical members of the S8A subfamily of subtilases (4). The type-example for subfamily S8B is kexin from Saccharomyces cerevisiae, which was identified as the first SBT from eukaryotes and the first with narrow specificity for dibasic cleavage sites (5). Dibasic cleavage specificity is typically found also in the seven kexin-related proprotein convertases (PCs) in mammals (6). In contrast, all plant SBTs belong to subfamily S8A. They are thus more closely related to bacterial subtilisins than to kexin, but they comprise both, general proteases for protein turnover as well as processing enzymes for limited proteolysis at highly specific sites (7,8).Early structural investigations of subtilisin E showed that it is produced with an N-terminal signal peptide targeting the protein to the periplasmic spac...

Two banknotes and two coins of the New Taiwan Dollar are infrequently (if at all) used in Taiwan when people make cash payments. This note examines the effect of this behavior on the efficiency of cash payments. The results are compared with the Euro, where the two highest and two lowest tokens are also rarely used. We find for Taiwan that inefficiency increases with 60.7%, while for the Euro it is only 25.3%. The main reason is that two of the rarely used coins and notes in Taiwan are in the middle of the denominational range, whereas for the Euro, these tokens concern the ends of that range.

We propose a simple and reproducible methodology to create a single equation forecasting model (SEFM) for low-frequency macroeconomic variables. Our methodology is illustrated by forecasting annual real GDP growth rates for 52 African countries, where the data are obtained from the World Bank and start in 1960. The models include lagged growth rates of other countries, as well as a cointegration relationship to capture potential common stochastic trends. With a few selection steps, our methodology quickly arrives at a reasonably small forecasting model per country. Compared with benchmark models, the single equation forecasting models seem to perform quite well.

The current (as of 2012) denominational range of the Malaysian ringgit has banknotes of RM1, 5, 10, 20, 50 and 100, but no RM2. The previous range (1996) carried RM1, 2, 5, 10, 50 and 100, but no RM20. We compare the efficiency of these two ranges with a full range like the Euro has, that is, 1, 2, 5, 10, 20, 50 and 100. We estimate that if the Bank Negara Malaysia would reintroduce an RM2 banknote, the efficiency of the payment system in Malaysia would increase substantially.

Professional forecasters can rely on an econometric model to create their forecasts. It is usually unknown to what extent they adjust an econometric model-based forecast. In this paper we show, while making just two simple assumptions, that it is possible to estimate the persistence and variance of the deviation of their forecasts from forecasts from an econometric model. A key feature of the data that facilitates our estimates is that we have forecast updates for the same forecast target. An illustration to consensus forecasters who give forecasts for GDP growth, inflation and unemployment for a range of countries and years suggests that the more a forecaster deviates from a prediction from an econometric model, the less accurate are the forecasts.