Streptomyces mobaraensis secretes a Ca2+‐independent transglutaminase (TGase) that is activated by removing an N‐terminal peptide from a precursor protein during submerged culture in a complex medium [Pasternack, R., Dorsch, S., Otterbach, J. T., Robenek, I. R., Wolf, S. & Fuchsbauer, H.‐L. (1998) Eur. J. Biochem. 257, 570–576]. However, an activating protease could not be identified, probably because of the presence of a 14‐kDa protein (P14) belonging to the Streptomyces subtilisin inhibitor family. In contrast, if the microorganism was allowed to grow on a minimal medium, several soluble proteases were extracted, among them the TGase‐activating protease (TAMEP). TAMEP was purified by sequential chromatography on DEAE‐ and Arg‐Sepharose and used to determine the cleavage site of TGase. It was clearly shown that the peptide bond between Phe(−4) and Ser(−5) was hydrolyzed, indicating that at least one additional peptidase is necessary to complete TGase processing, even if TAMEP cleavage was sufficient to obtain total activity. Sequence analysis from the N‐terminus of TAMEP revealed the close relationship to a zinc endo‐protease from S. griseus. The S. griseus protease differs from other members of the M4 protease family, such as thermolysin, in that it may be inhibited by the Streptomyces subtilisin inhibitor. P14 likewise inhibits TAMEP in approximately equimolar concentrations, suggesting its important role in regulating TGase activity.

The food industry, along with the consumers, is interested in plant‐based diet because of its health benefits and environmental sustainability. Vicia faba L. (V. faba) is a promising source of pulse proteins for the human diet and can yield potential nutritional and functional ingredients, namely, flours, concentrates, and isolates, which are relevant for industrial food applications. Different processes produce and functionalize V. faba ingredients relevant for industrial food applications, along with various alternatives within each unit operation used in their production. Processing modifies functional properties of the ingredients, which can occur by (i) changing in overall nutritional composition after processing steps and/or (ii) modifying the structure and conformation of protein and of other components present in the ingredients. Furthermore, V. faba limitations due to off‐flavor, color, and antinutritional factors are influenced by ingredient production and processing that play a significant role in their consumer acceptability in foods. This review attempts to elucidate the influence of different ways of processing on the functional, sensory, and safety aspects of V. faba L. ingredients, highlighting the need for further research to better understand how the food industry could improve their utilization in the market.

Transglutaminase (TGase) from Streptomyces mobaraensis is secreted as a precursor protein which is completely activated by the endoprotease TAMEP, a member of the M4 protease family [Zotzel, J., Keller, P. & Fuchsbauer, H.‐L. (2003) Eur. J. Biochem. 270, 3214–3222]. In contrast with the mature enzyme, TAMEP‐activated TGase exhibits an additional N‐terminal tetrapeptide (Phe‐Arg‐Ala‐Pro) suggesting truncation, at least, by a second protease. We have now isolated from the culture broth of submerged colonies a tripeptidyl aminopeptidase (SM‐TAP) that is able to remove the remaining tetrapeptide. The 53‐kDa peptidase was purified by ion‐exchange and phenyl‐Sepharose chromatography and subsequently characterized. Its proteolytic activity was highest against chromophoric tripeptides at pH 7 in the presence of 2 mm CaCl2. EDTA and EGTA (10 mm) both diminished the proteolytic activity by half. Complete inhibition was only achieved with 1 mm phenylmethanesulfonyl fluoride, suggesting that SM‐TAP is a serine protease. Alignment of the N‐terminal sequence confirmed its close relation to the Streptomyces TAPs. That removal of Phe‐Arg‐Ala‐Pro from TAMEP‐activated TGase by SM‐TAP occurs in a single step was confirmed by experiments using various TGase fragments and synthetic peptides. SM‐TAP was also capable of generating the mature N‐terminus by cleavage of RAP‐TGase. However, AP‐TGase remained unchanged. As SM‐TAP activity against chromophoric amino acids such as Pro‐pNA or Phe‐pNA could not be detected, the tetrapeptide of TAMEP‐activated TGase must be removed without formation of an intermediate.

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Aging represents a major risk factor for developing neurodegenerative diseases such as Alzheimer's disease (AD). As components of the Mediterranean diet, olive polyphenols may play a crucial role in the prevention of AD. Since mitochondrial dysfunction acts as a final pathway in both brain aging and AD, respectively, the effects of a mixture of highly purified olive secoiridoids were tested on cognition and ATP levels in a commonly used mouse model for brain aging. Over 6 months, female NMRI mice (12 months of age) were fed with a blend containing highly purified olive secoiridoids (POS) including oleuropein, hydroxytyrosol and oleurosid standardized for 50 mg oleuropein/kg diet (equivalent to 13.75 mg POS/kg b.w.) or the study diet without POS as control. Mice aged 3 months served as young controls. Behavioral tests showed deficits in cognition in aged mice. Levels of ATP and mRNA levels of NADH-reductase, cytochrome-c-oxidase, and citrate synthase were significantly reduced in the brains of aged mice indicating mitochondrial dysfunction. Moreover, gene expression of Sirt1, CREB, Gap43, and GPx-1 was significantly reduced in the brain tissue of aged mice. POS-fed mice showed improved spatial working memory. Furthermore, POS restored brain ATP levels in aged mice which were significantly increased. Our results show that a diet rich in purified olive polyphenols has positive long-term effects on cognition and energy metabolism in the brain of aged mice.