Development of a peptide reactivity assay for screening botanicals and natural substances: Proof of concept studies.

Consumer products containing botanicals or natural substances (BNS) are often preferred because there is a perception that 'natural' is safe. As with any product ingredient, a thorough safety assessment must be conducted, including a determination of skin sensitization potential. A modification of the Peroxidase Peptide Reactivity Assay (PPRA) was explored for screening BNS (B-PPRA) for their reactivity to a model cysteine peptide.

Safety assessment scheme for menstrual cups and application for the evaluation of a menstrual cup comprised of medical grade silicone.

Background: Ensuring menstrual cup safety is paramount, yet a menstrual cup safety assessment scheme is lacking. This paper presents a quadripartite scheme, showing how it can be applied.

Methods: The Tampax Menstrual Cup was evaluated in the safety assessment scheme: (1) Biocompatibility and chemical safety of cup constituents.

UHPLC-MS/HRMS method for the quantitation of pyrithione metabolites in human urine.

Pyrithione glucuronide (PTG) and 2-thiopyridine glucuronide (ThPG) have been reported to be the major urinary metabolites in multiple animal species following administration of zinc pyrithione (ZnPT). However, the formation of these metabolites has never been confirmed in humans. A simple and rugged ultra-high-performance liquid chromatography high resolution mass spectrometry (UHPLC-MS/HRMS) method was developed and validated for the quantification of PTG and ThPG to investigate human metabolism of pyrithione following topical application of ZnPT as a shampoo.

The role of mass spectrometry and related techniques in the analysis of extractable and leachable chemicals.

In addition to degradation products, impurities, and exogenous contaminants, industries such as pharmaceutical, food, and others must concern themselves with leachables. These chemicals can derive from containers and closures or migrate from labels or secondary containers and packaging to make their way into products. Identification and quantification of extractables (potential leachables) and leachables, typically trace level analytes, is a regulatory expectation intended to ensure consumer safety and product fidelity.

Assessing the biodegradability of microparticles disposed down the drain.

Microparticles made from naturally occurring materials or biodegradable plastics such as poly(3-hydroxy butyrate)-co-(3-hydroxy valerate), PHBV, are being evaluated as alternatives to microplastics in personal care product applications but limited data is available on their ultimate biodegradability (mineralization) in down the drain environmental compartments. An OECD 301B Ready Biodegradation Test was used to quantify ultimate biodegradability of microparticles made of PHBV foam, jojoba wax, beeswax, rice bran wax, stearyl stearate, blueberry seeds and walnut shells. PHBV polymer was ready biodegradable reaching 65.

Yeast Trm7 interacts with distinct proteins for critical modifications of the tRNAPhe anticodon loop.

Post-transcriptional modification of the tRNA anticodon loop is critical for translation. Yeast Trm7 is required for 2'-O-methylation of C(32) and N(34) of tRNA(Phe), tRNA(Trp), and tRNA(Leu(UAA)) to form Cm(32) and Nm(34), and trm7-Δ mutants have severe growth and translation defects, but the reasons for these defects are not known. We show here that overproduction of tRNA(Phe) suppresses the growth defect of trm7-Δ mutants, suggesting that the crucial biological role of Trm7 is the modification of tRNA(Phe).

Removal of 3'-phosphate group by bacterial alkaline phosphatase improves oligonucleotide sequence coverage of RNase digestion products analyzed by collision-induced dissociation mass spectrometry.

RNase mapping by nucleobase-specific endonucleases combined with liquid chromatography/tandem mass spectrometry (LC/MS/MS) is a powerful analytical method for characterizing ribonucleic acids (RNAs). Endonuclease digestion of RNA yields products that contain a 3'-terminal phosphate group. MS/MS via collision-induced dissociation (CID) of these digestion products on a linear ion trap generates fragmentation pathways that include the loss of phosphoric acid (-H(3)PO(4); -98 u), which does not provide information about the sequence of the digestion products and can reduce ion abundance from other pathways that provide sequence information.

Formation of m2G6 in Methanocaldococcus jannaschii tRNA catalyzed by the novel methyltransferase Trm14.

The modified nucleosides N(2)-methylguanosine and N(2)(2)-dimethylguanosine in transfer RNA occur at five positions in the D and anticodon arms, and at positions G6 and G7 in the acceptor stem. Trm1 and Trm11 enzymes are known to be responsible for several of the D/anticodon arm modifications, but methylases catalyzing post-transcriptional m(2)G synthesis in the acceptor stem are uncharacterized. Here, we report that the MJ0438 gene from Methanocaldococcus jannaschii encodes a novel S-adenosylmethionine-dependent methyltransferase, now identified as Trm14, which generates m(2)G at position 6 in tRNA(Cys).

Sequence analysis of peptide:oligonucleotide heteroconjugates by electron capture dissociation and electron transfer dissociation.

Mass spectrometry analysis of protein-nucleic acid cross-links is challenging due to the dramatically different chemical properties of the two components. Identifying specific sites of attachment between proteins and nucleic acids requires methods that enable sequencing of both the peptide and oligonucleotide component of the heteroconjugate cross-link. While collision-induced dissociation (CID) has previously been used for sequencing such heteroconjugates, CID generates fragmentation along the phosphodiester backbone of the oligonucleotide preferentially.

Agmatidine, a modified cytidine in the anticodon of archaeal tRNA(Ile), base pairs with adenosine but not with guanosine.

Modification of the cytidine in the first anticodon position of the AUA decoding tRNA(Ile) (tRNA2(Ile)) of bacteria and archaea is essential for this tRNA to read the isoleucine codon AUA and to differentiate between AUA and the methionine codon AUG. To identify the modified cytidine in archaea, we have purified this tRNA species from Haloarcula marismortui, established its codon reading properties, used liquid chromatography-mass spectrometry (LC-MS) to map RNase A and T1 digestion products onto the tRNA, and used LC-MS/MS to sequence the oligonucleotides in RNase A digests. These analyses revealed that the modification of cytidine in the anticodon of tRNA2(Ile) adds 112 mass units to its molecular mass and makes the glycosidic bond unusually labile during mass spectral analyses.