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[Music]

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yeah just a real quick plug that I and a

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lot of my courts are cool researchers

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chemical origins apply and we're proud

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I'm a proud member of the Center for

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chemical evolution I'm kind of like what

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a body was saying that we understand

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that biopolymers are the constituents of

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life and we look at poly nucleic acids

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polysaccharides polypeptides and really

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we look at proto poly nucleic acids

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polypeptides and I'll be talking about

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our proto polypeptides and we really

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like to embrace the evolution and the

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transformation of these systems so to

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put the proto in polypeptide me up to

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motivate that we have to consider some

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of the challenges of poly condensation

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of amino acids in the early Earth

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environment the direct condensation does

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require high temperatures it can also be

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achieved with a complex catalyst that

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may not be periodically plausible and of

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course sometimes called the dkp trap

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this cyclic dimer that occurs after you

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get your first condensation that is a

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trap towards further linear polymers of

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amino acids so we look for we look in

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two places meteorite examples and and

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also spark experiments are two of

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probably many and we have to acknowledge

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that the prebiotic molecular inventory

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is more diverse than the Vinge's what we

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have in our bodies right now so this an

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analog to amino acids hydroxy acids are

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quite similar except they have a

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hydroxyl group and therefore I can

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deform ester bonds instead of Arab bonds

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which are you know chemically distinct

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and these are plausible of course

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because they do appear in samples like

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the Murchison meteorite and

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in abundance in spark to charge model

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prebiotic systems and so what we have

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found in our search to have this proto

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apply peptide is an ester mediated amide

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bond formation

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so in evaporative conditions at mild

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temperatures eighty five and we've

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explored some of the mperatures as well

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but we as I've mentioned here the direct

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peptide formation can lead to the cyclic

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dimerization kind of the end of that

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cycle we don't see in Mason conditions

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we don't see applied glycine or poly

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amino acids but hydroxy I think there's

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actually lack of gasps what are we

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talking about a lot today they wrap

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readily form polyesters in these

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conditions so if we combine these two

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this co polymerizing system at this at

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this after the carbon of this ester site

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is activated for the nucleophilic attack

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by the amino acid and we get this we

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call exchange and this can be repeated

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so this esterification exchange until we

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get something that has a mix and ester

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backbone that we refer to as a deputy

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peptide and this can go on indefinitely

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and we get shown here a wide variety of

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sequences and compositions of oligomers

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with appreciable lengths and this can

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just go off like a shot so we get these

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copolymers that like I said have ester

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and the deck bones so way back to the

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Brinell hypothesis but just that

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minerals have been as ever-present steam

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in prebiotic chemistry their ubiquity

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their diversity and the unique dynamics

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that go on at the inner feet at the

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interface necessitate their their

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consideration and especially in

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evaporative systems will be drive off

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water to promote condensation if and you

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know in dilutes systems which are very

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plausible that the substrates will

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almost like always be in contact with

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the molecules

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their interactions need to be considered

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so focusing on the composition of deputy

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peptides you can have for say a six mark

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and anything from a holy peptide to

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something a polyester and of course the

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EPI peptides are somewhere in between so

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using mass spectrometry we can have a

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reaction and then understand the

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relative abundances of the different

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compositions here the dominant species

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present in this population is a six

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month six MERS has three lactic acids

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and in this case three glycine's and

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what we can also do is compare different

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conditions so an addition of in this

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case fumed silica presents a completely

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different composition distribution here

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we see that the dominant species only

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contains one hydroxy acid lactic acid so

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this is much more peptide like in

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character and through other mass

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spectometry means it's likely that this

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one hydroxy acid is actually on the end

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so we have a core of amino acids a

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peptide so this enrichment of amino

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acids is very important it's very

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interesting and occurs in the presence

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of silica so just some quick

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experimental notes this reaction a lot

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of you have been doing at 85 degrees

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Celsius and open file and this is an

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acidic pH s and this not only works for

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this enrichment of amino acids not only

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occurs for a glycine lactic acid system

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but also alanine so I have more slightly

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more complex amino acid at 85 we see

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that there from the black red and the

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Rev the black and red inset that a lower

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atomic mass is actually something that

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is more peptide rich because nitrogen

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has a lower tonic past and oxygen and

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for Allen again even at higher

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temperatures that the distributions are

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distinct and there are other ways to

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verify this

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acid and enrichment in the presence of

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silica we can look at NMR and I won't go

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into how we assign these Peaks but we

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can identify these key bonding motifs

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some associated esters and we see in the

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first one that is present in the no

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substrate control and its absence in the

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silica samples something that

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corresponds to internal amid linkages is

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much more abundant in the silicon

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containing samples than in the control

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and another example of a motif

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associated with polyesterification that

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is present in the control and not the

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silicon panning samples so that's that

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was very interesting and so our next

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step and to kind of understand maybe how

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this was happening was to kind of break

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up the reaction in two steps so first we

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were reacting the silica with the

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hydroxy acid lactic acid incubated it

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then watched it to remove maybe any non

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covalently bound species and then added

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our amino acid afterwards and what we

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got was a population of depth C peptides

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that had no esters so they only won a

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lactic acid on the C terminus and so

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that if we were to form these poly or

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these Amin's we would have to have had a

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an ester present to be the activator and

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so that kind of got us thinking of what

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may be occurring on a hydroxyl

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terminated silica surface that we could

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perhaps have formed these inter facial

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esters that when the glycine is present

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later these were active sites as I

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expressed earlier for ester Damon

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exchange and that we were able to form a

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Dead Sea peptide so - to begin to

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confirm this we thought about modifying

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our hydroxy acid so we now it's a

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methoxy propionic acid so this is now a

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mono functional molecule that cannot

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cannot participate in esterification

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though for other Pitts purposes such as

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the the acidity and the pKa of the acid

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are quite similar to lactic acid we

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reacted that with an amino acid and as

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it turns out in the absence of silica we

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do not get only trace amounts of the

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condensation products but in the

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presence of silica we get you know up to

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four or so glycine's attached to this

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one to methoxy propionic acid and this

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suggests that the silica can participate

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in the formation of an ester therefore

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an active site that can allow for an

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amid synthesis and at the temperatures

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and also we can look at other or at

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other substrates some minerals tio2 and

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hydroxide and see that titania does

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produce some economization products and

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all the NOx hydroxide does not and I

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think that's interesting so just to

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conclude that we are able to form deputy

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peptides in presence of silica and that

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the presence of silica enriches the

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population in amino acids both glycine

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alanine we can be sure about that

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because ester linkages are reduced in

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presence of silica and ammon linkages

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are increased and that it is suggested

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that the the amide synthesis in the

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presence of silica is actually

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facilitated by a interfacial ester and

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so going back to the last level we

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showed some other minerals what

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characteristic of the mineral would

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would be most predictive of its ability

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to enrich the system a peptide farming

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system definitely forming system with

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amino acids is unclear right now but

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that's the target of present work and

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that's yeah it's like that right now

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thank you okay cool

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that was a great talk thank you I have a

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question about a kind of comment

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question about silica that's because we

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think that silica availability on earth

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has changed a lot through time now it's

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controlled a lot by biology because

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there's shale formation so do you think

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that because silica might have been more

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available back in Earth history would

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that affect your your results so a lot

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of these studies didymus fused silica

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which I wouldn't even consider formally

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a mineral that's you know pyrolysis

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created the question of the abundance of

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silica I'm not exactly sure I think

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they're probably other minerals that are

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far more abundant co2 may have been one

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I I don't I don't mean to say that silk

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is the only way that we can enrich I

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mean you know the use any mineral to

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enrich deputy peptide systems with amino

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acids you can cycle these you can add

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more of one monomer but the chemistry

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with a mineral and a deputy peptide

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system needs to be studied and is

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distinct from a mineral and a purely

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amino acid system which has been looked

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at extensively in the past and so I

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distinctively limiting the the length of

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the oligomers that you can form one of

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them could be I mean besides besides

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like a monomer I think solubility of the

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if we get too too large then they the

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oligomers may conform in some way where

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the